Hello Programmers/Coders, Today we are going to share solutions of Programming problems of HackerRank of Programming Language SQL. At Each Problem with Successful submission with all Test Cases Passed, you will get an score or marks. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.
In this post, you will find the solution for Average Population of Each Continent in SQL-HackerRank Problem. We are providing the correct and tested solutions of coding problems present on HackerRank. If you are not able to solve any problem, then you can take help from our Blog/website.
Use “Ctrl+F” To Find Any Questions Answer. & For Mobile User, You Just Need To Click On Three dots In Your Browser & You Will Get A “Find” Option There. Use These Option to Get Any Random Questions Answer.
Introduction To SQL
SQL stands for Structured Query Language. SQL is used to create, remove, alter the database and database objects in a database management system and to store, retrieve, update the data in a database. SQL is a standard language for creating, accessing, manipulating database management system. SQL works for all modern relational database management systems, like SQL Server, Oracle, MySQL, etc.
- It is a standard language for Relational Database System. It enables a user to create, read, update and delete relational databases and tables.
- All the RDBMS like MySQL, Informix, Oracle, MS Access and SQL Server use SQL as their standard database language.
- SQL allows users to query the database in a number of ways, using English-like statements.
Link for the Problem – Average Population of Each Continent – Hacker Rank Solution
Average Population of Each Continent – Hacker Rank Solution
Problem:
Given the CITY and COUNTRY tables, query the names of all the continents (COUNTRY.Continent) and their respective average city populations (CITY.Population) rounded down to the nearest integer.
Note: CITY.CountryCode and COUNTRY.Code are matching key columns.
Input Format
The CITY and COUNTRY tables are described as follows:


Average Population of Each Continent – Hacker Rank Solution
SELECT o.CONTINENT, FLOOR(AVG(i.POPULATION)) FROM CITY AS i JOIN COUNTRY AS o ON i.COUNTRYCODE=o.CODE GROUP BY o.CONTINENT;
Howdy very cool website!! Guy .. Excellent .. Superb .. I will bookmark your site and take the feeds additionally…I am glad to seek out a lot of helpful info here within the post, we want develop extra strategies on this regard, thank you for sharing.
Usually I do not read post on blogs, but I wish to say that this write-up very forced me to try and do it! Your writing style has been amazed me. Thanks, quite nice post.
Wow! Thank you! I permanently needed to write on my blog something like that. Can I implement a part of your post to my blog?
Thank you a lot for giving everyone an extremely marvellous possiblity to read critical reviews from this blog. It can be very superb and as well , jam-packed with amusement for me personally and my office peers to search the blog particularly 3 times in a week to learn the latest items you will have. And indeed, I am at all times astounded with all the spectacular ideas you give. Certain 2 facts in this posting are particularly the most suitable we have had.
I have not checked in here for some time because I thought it was getting boring, but the last several posts are good quality so I guess I will add you back to my everyday bloglist. You deserve it my friend 🙂
Hiya very cool website!! Guy .. Excellent .. Superb .. I will bookmark your site and take the feeds additionallyKI’m happy to seek out so many helpful info right here within the put up, we want work out more techniques in this regard, thanks for sharing. . . . . .
Very interesting details you have remarked, appreciate it for posting. “Without courage, wisdom bears no fruit.” by Baltasar Gracian.
you have a great blog here! would you like to make some invite posts on my blog?
It’s really a great and helpful piece of information. I am glad that you shared this useful information with us. Please keep us up to date like this. Thanks for sharing.
You made some good points there. I did a search on the subject and found most guys will approve with your website.
Great post, you have pointed out some excellent points, I also think this s a very superb website.
Would you be interested in exchanging links?
Hi , I do believe this is an excellent blog. I stumbled upon it on Yahoo , i will come back once again. Money and freedom is the best way to change, may you be rich and help other people.
whoah this blog is great i love reading your articles. Keep up the great work! You know, a lot of people are looking around for this info, you could help them greatly.
Wow! Thank you! I continually wanted to write on my website something like that. Can I take a fragment of your post to my website?
Hello I am so delighted I found your website, I really found you by mistake, while I was researching on Aol for something else, Regardless I am here now and would just like to say thank you for a fantastic post and a all round thrilling blog (I also love the theme/design), I don’t have time to read through it all at the moment but I have book-marked it and also added in your RSS feeds, so when I have time I will be back to read a lot more, Please do keep up the great job.
F*ckin¦ awesome things here. I am very glad to peer your article. Thanks so much and i am looking ahead to contact you. Will you please drop me a e-mail?
naturally like your website but you have to check the spelling on several of your posts. Many of them are rife with spelling issues and I find it very bothersome to tell the truth nevertheless I’ll definitely come back again.
Heya i am for the first time here. I found this board and I to find It really helpful & it helped me out a lot. I am hoping to provide one thing back and aid others like you aided me.
Some really good info , Gladiolus I noticed this. “Now hatred is by far the longest pleasure men love in haste but they detest at leisure.” by George Gordon Byron.
wonderful points altogether, you just gained a new reader. What would you recommend about your submit that you made some days in the past? Any certain?
cialis online cialis tadalafil 5mg low cost ed pills
you are truly a good webmaster. The web site loading speed is amazing. It sort of feels that you are doing any distinctive trick. Moreover, The contents are masterpiece. you have performed a magnificent task in this subject!
duricef sale buy cefadroxil 500mg pill order proscar 5mg online
estrace 2mg oral prazosin order buy prazosin 2mg online cheap
purchase diflucan pill fluconazole 200mg for sale cipro 500mg over the counter
buy generic vermox online buy tadalis without prescription tadalafil 20mg tablet
order metronidazole pills metronidazole cost cephalexin online order
buy avanafil without prescription avanafil for sale online voltaren uk
cleocin us order cleocin 300mg pills fildena canada
indocin 50mg canada buy lamisil 250mg online cheap where can i buy cefixime
buy nolvadex online nolvadex generic buy generic cefuroxime
purchase trimox online cheap buy generic amoxicillin 500mg biaxin buy online
buy generic bimatoprost careprost order online buy trazodone pills
buy generic catapres 0.1mg oral tiotropium bromide 9mcg tiotropium bromide online buy
There are dozens of online Bitcoin casinos that feature poker games in their portfolio. Our guide has reviewed the top Bitcoin poker sites – which include BetOnline Lucky Block, CoinPoker, BC.Game, CloudBet, Bovado, and more. Thanks to its big-money tournaments, newbie-friendly approach, and one of the best poker bonuses, PokerStars took the top spot as UK’s best poker site. Still, all of the other online poker platforms listed below are just as good. State-regulated online poker platforms will bring legal online poker to Michigan for the first time. Playing at a legal mobile poker site presents many advantages over putting your money on an illegal poker site. There are many online poker sites to choose among and also a lot of different real money poker games. First of all, poker is a game where all players have different preferences. You play at different levels, you play different poker games and you like different designs and features. So it’s impossible for one specific site to be the best for everyone. When we rate and rank real money online poker sites, we do so according to specific guidelines which are designed to suit as many players as possible.
http://www.ures.co.kr/bbs/board.php?bo_table=free&wr_id=47410
Yes, real money online slots are legit. To protect your money, we only recommend sites with trusted banking methods and reliable payouts. As part of their security measures, many legit casinos request a copy of your ID. Customer service then verifies your account info to protect you before processing any withdrawals. Many things can affect how lucrative an online slot game can be, from RTPs to how much you bet per spin. If you want to increase your chances of winning real money, keep the following factors in mind. Playing slots online is great for winning real money, but before you do this, try before you buy. Far too often, we see newbies unfamiliar with game mechanics, resulting in them losing valuable winnings. Therefore, before betting any real money, check if your online casino offers a free credit test and learn how the slot works first.
sildenafil online buy brand suhagra purchase sildalis sale
minocycline 100mg sale hytrin us order pioglitazone 15mg online cheap
buy arava generic sildenafil 50mg buy azulfidine 500mg pill
purchase accutane online cheap order isotretinoin 40mg pills order generic azithromycin 500mg
buy tadalafil 10mg sale buy viagra sale order cialis 5mg online
ivermectin 6mg pills for humans buy prednisone pills for sale order prednisone 10mg pill
order generic azithromycin 500mg azithromycin cheap buy neurontin 600mg online
order furosemide pill albuterol medication albuterol oral
brand vardenafil where can i buy vardenafil plaquenil 200mg for sale
ramipril 5mg over the counter oral etoricoxib 120mg order arcoxia 120mg generic
buy levitra 10mg pill vardenafil for sale online buy plaquenil paypal
buy mesalamine 800mg generic irbesartan 150mg price buy irbesartan 150mg generic
olmesartan buy online order depakote 250mg online cheap depakote 500mg pills
temovate sale purchase temovate without prescription order amiodarone 200mg generic
diamox 250 mg sale order imdur 40mg sale azathioprine over the counter
lanoxin 250mg usa micardis 20mg generic molnunat 200mg drug
coreg order online cenforce ca aralen 250mg usa
buy naproxen tablets purchase prevacid online cheap buy generic prevacid 15mg
buy albuterol proventil 100mcg pill buy pyridium 200 mg generic
purchase baricitinib generic buy atorvastatin 80mg without prescription buy generic atorvastatin 40mg
singulair 5mg without prescription avlosulfon order buy dapsone 100 mg online cheap
buy cheap generic adalat cost nifedipine brand fexofenadine 180mg
buy cheap generic norvasc buy norvasc 10mg generic order omeprazole online cheap
priligy 30mg brand order orlistat 120mg generic xenical 60mg without prescription
metoprolol 100mg drug methylprednisolone 8 mg tablet methylprednisolone medication
brand diltiazem buy zyloprim 300mg without prescription zyloprim 300mg cheap
generic aristocort 4mg buy loratadine 10mg online cost claritin
buy crestor cheap where to buy rosuvastatin without a prescription order motilium 10mg pills
order ampicillin 250mg generic ampicillin over the counter purchase metronidazole pills
order sumycin online cheap tetracycline without prescription oral ozobax
Hey there! Do you know if they make any plugins to assist with Search Engine Optimization? I’m trying to get my blog to rank for some targeted keywords but I’m not seeing very good gains. If you know of any please share. Cheers!
buy generic bactrim 960mg oral clindamycin order cleocin 150mg online cheap
buy generic ketorolac over the counter toradol 10mg drug buy inderal cheap
whoah this blog is excellent i love reading your articles. Keep up the good work! You know, many people are looking around for this information, you can help them greatly.
erythromycin online buy buy tamoxifen 20mg online cheap tamoxifen 10mg pill
plavix 75mg uk methotrexate 10mg over the counter warfarin online
buy reglan 10mg without prescription esomeprazole 20mg usa buy nexium generic
buy generic budesonide for sale cefuroxime pills purchase careprost
order topiramate online cheap levofloxacin generic order levaquin 250mg generic
order robaxin pill buy robaxin pills for sale generic suhagra
order avodart pill order meloxicam buy mobic online
buy sildenafil 50mg pill sildalis uk estradiol us
cheap celebrex 100mg celebrex 200mg cost order zofran generic
buy lamotrigine 50mg online buy vermox for sale minipress 2mg drug
spironolactone where to buy buy spironolactone 100mg order valtrex pills
retin medication generic retin cream order avana generic
brand proscar 5mg generic propecia 5mg sildenafil 50mg oral
oral tadacip 10mg order tadacip online cheap buy indocin 50mg for sale
Yay google is my world beater helped me to find this outstanding website ! .
888poker is blazing a trail with players in New Jersey who play online poker for real money. Enjoy exciting games, fun-filled features, and massive poker pots! Gambling can be addictive. Play responsibly. BetMGM Poker and WSOP only offer hold’em and Omaha. PokerStars is the only option for players looking to play other games, including mixed-game formats. PokerStars has the following cash games available: Play poker for real money at our top recommended sites. Ignition Online Casino is the leading online poker room for Australian players, offering a huge range of cash games and tournaments with buy-ins to suit every budget. So whether you’re a beginner or a pro, our selection of real-money online poker games has something for everyone.
http://www.otrabotka.com/goods/detail.php?id=131&print=Y
Visit our live poker room where poker players can pull up a seat and play 1 3 No Limit Texas Hold’em and higher, 1 3 Pot Limit Omaha and higher. 6 Card Bonus – player’s objective is to make the best five-card poker hand by combining the player’s three cards with the dealer’s three cards. Pays out when ‘Three of a kind’ or better are made up out of the six cards dealt in the table. The Payout is according to the hand rank according to the Payout table section below. You place the bet before your cards are dealt. Typically there will be a 21+3 box on the table in which you place your stake for the side bet. Visit our live poker room where poker players can pull up a seat and play 1 3 No Limit Texas Hold’em and higher, 1 3 Pot Limit Omaha and higher.
cost tadalafil online ed medications men’s ed pills
lamisil buy online cefixime 200mg cheap where to buy amoxicillin without a prescription
sulfasalazine online calan sale calan 240mg price
arimidex online buy clonidine online cheap buy catapres online
depakote over the counter purchase diamox online cheap buy isosorbide 20mg online
È semplice, ogni giorno imposteremo sul nostro sito i link che ti permetteranno di ricevere Giri gratuiti (Free Spin) e oro sul gioco Coin Master. com-moonactive-coinmaster-358222-65026403-20f8c169b696c9bf375e48ac91bcb4d4.apk No, i collegamenti ai giri gratuiti emessi nel 2019 non sono più validi. I link Coin Master Free Spins sono validi solo per 3 giorni, quindi dovresti cercare i link Spins e Coins recenti per ogni giorno. Solo i collegamenti ai giri gratuiti in Coin Master 2022 sono quelli da cercare. COSMIN, 2020-04-23 22:26:52 E possible avere dei free spin Per ottenere grandiose offerte e bonus esclusivi su Coin Master ti basterà seguire la loro pagina Facebook. In questo modo avrai accesso a una serie di vantaggi che ti permetteranno di giocare gratuitamente ottenendo spin gratuiti, massimizzando tutto ciò che può offrirti Coin Master.2. Acquista in maniera intelligente!Hai intenzione di acquistare un pacchetto per massimizzare la tua esperienza suCoin Master? Allora fallo in maniera intelligente!
http://www.gohammer.co.kr/bbs/board.php?bo_table=free&wr_id=60993
Mostra tutti >> Tra tutti i video poker online gratis che abbiamo testato, Aces & Faces ci è sembrato interessante per la sua semplicità di gioco, unita a una paytable in cui troverete premi extra. In questa versione di video poker gratis troverete infatti un’enfasi maggiore posta sui simboli delle figure e degli assi: i poker di J, Q o K pagano infatti 40 – quasi il doppio dei numeri – e trovando 4 assi vincerete 80 volte la vostra puntata. Come nella maggior parte dei video poker a soldi veri o in versione demo, la combinazione minima pagante è il Jacks or Better, che paga dalla coppia di fanti in poi – escludendo le coppie numeriche. Ma cosa sono i bonus senza deposito? Come dice il loro nome sono bonus che non prevedono nessun deposito da parte del giocatore, ma sono dei soldi che vengono accreditati al giocatore soltanto perché si è registrato alla piattaforma. Di solito questa offerta, in denaro o sotto forma di giri gratis, non è utilizzabile in tutte le aree del casinò, ma viene limitata ad alcuni giochi, come slot machine, roulette e appunto il poker.
buy antivert 25mg sale minocin pill buy minocycline pills for sale
buy imuran tablets buy azathioprine sale order telmisartan generic
order molnunat sale naprosyn 250mg uk order omnicef 300mg online
erectile dysfunction drug buy viagra 100mg sale buy viagra without prescription
where can i buy lansoprazole prevacid 30mg uk pantoprazole 40mg canada
ed pills otc oral tadalafil 5mg tadalafil 40mg sale
buy phenazopyridine pills for sale singulair 5mg sale symmetrel online buy
buy ed pills usa cialis ca order cialis without prescription
dapsone 100mg tablet buy avlosulfon 100mg generic order perindopril for sale
Heya i’m for the primary time here. I found this board and I in finding It really useful & it helped me out much. I am hoping to give something back and help others like you aided me.
buy allegra generic buy generic allegra over the counter generic glimepiride
terazosin 5mg oral generic hytrin 1mg order tadalafil 20mg sale
irbesartan generic avapro 150mg us buspirone ca
order cordarone online coreg for sale phenytoin without prescription
order oxybutynin 2.5mg pill buy generic fosamax 35mg purchase alendronate sale
praziquantel 600 mg cheap cyproheptadine drug purchase cyproheptadine generic
purchase nitrofurantoin for sale pamelor 25 mg cost pamelor 25mg drug
order fluvoxamine 100mg sale duloxetine 40mg without prescription oral duloxetine
Hi, just required you to know I he added your site to my Google bookmarks due to your layout. But seriously, I believe your internet site has 1 in the freshest theme I??ve came across. It extremely helps make reading your blog significantly easier.
buy glucotrol 10mg online glucotrol 10mg over the counter betamethasone 20 gm drug
generic acetaminophen 500 mg cost famotidine buy pepcid 20mg pill
buy anafranil 50mg generic progesterone 200mg brand prometrium 200mg for sale
cost tacrolimus 1mg remeron 15mg over the counter order requip 2mg sale
order tinidazole online cheap buy olanzapine online cheap generic nebivolol 20mg
calcitriol generic order tricor 200mg for sale order fenofibrate pills
order diovan 160mg clozapine over the counter order ipratropium 100 mcg online cheap
buy oxcarbazepine 600mg pill actigall 150mg uk buy urso paypal
decadron 0,5 mg for sale order decadron 0,5 mg purchase starlix pills
I really appreciate this post. I have been looking all over for this! Thank goodness I found it on Bing. You have made my day! Thank you again!
capoten 120mg generic buy capoten paypal purchase carbamazepine sale
bupropion 150 mg ca atomoxetine canada strattera 25mg drug
ciplox 500 mg sale order generic lincomycin 500 mg how to get cefadroxil without a prescription
cheap quetiapine 100mg quetiapine 50mg us escitalopram 20mg ca
can you buy prednisone online uk: http://prednisone1st.store/# prednisone 4mg
amoxicillin 800 mg price: [url=http://amoxicillins.com/#]generic amoxicillin over the counter[/url] amoxicillin 500 mg where to buy
https://propecia1st.science/# generic propecia without rx
where can i buy generic mobic no prescription: buy mobic pill – where buy mobic without prescription
can you get cheap mobic without a prescription: can i order cheap mobic pills – buying cheap mobic
order sarafem 20mg without prescription naltrexone order online buy letrozole 2.5mg pill
reliable canadian pharmacy reviews canadian pharmacy
can i buy generic mobic without a prescription [url=https://mobic.store/#]buy mobic[/url] buy generic mobic without rx
https://propecia1st.science/# cost cheap propecia without a prescription
order generic mobic for sale: how to get cheap mobic without rx – how to get cheap mobic without rx
where can i buy amoxicillin online where to buy amoxicillin pharmacy – order amoxicillin 500mg
get cheap propecia without a prescription buy cheap propecia without a prescription
https://pharmacyreview.best/# canadian pharmacy prices
ed medications list [url=https://cheapestedpills.com/#]erectile dysfunction medicines[/url] men’s ed pills
where buy generic mobic without dr prescription: where can i buy cheap mobic without a prescription – get cheap mobic without rx
buy zebeta 10mg online cheap buy myambutol 1000mg sale oxytetracycline 250 mg over the counter
top 10 pharmacies in india: mail order pharmacy india – india online pharmacy
https://indiamedicine.world/# indian pharmacy paypal
prescription drugs canada buy online: pharmacy rx world canada – canadian pharmacy price checker
order valcivir 500mg generic buy bactrim 480mg pills floxin oral
https://mexpharmacy.sbs/# п»їbest mexican online pharmacies
pharmacy rx world canada: my canadian pharmacy – cross border pharmacy canada
cefpodoxime without prescription generic cefpodoxime 100mg flixotide nasal sprays
http://indiamedicine.world/# Online medicine home delivery
real canadian pharmacy: canadian pharmacy online – 77 canadian pharmacy
order generic keppra 1000mg keppra 500mg over the counter sildenafil without a doctor’s prescription
https://certifiedcanadapharm.store/# canadian pharmacy mall
buy cialis online cheap tadalafil 20mg usa sildenafil canada
best canadian online pharmacy: canadian neighbor pharmacy – canadian pharmacy victoza
https://certifiedcanadapharm.store/# best online canadian pharmacy
canadian pharmacy india: buy drugs from canada – is canadian pharmacy legit
http://certifiedcanadapharm.store/# canada drugs reviews
ketotifen 1 mg uk order generic ziprasidone 40mg imipramine 25mg generic
https://azithromycin.men/# purchase zithromax online
cost of neurontin 600 mg: brand name neurontin – neurontin 800 mg
order minoxytop online cheap order tamsulosin online best ed drug
https://gabapentin.pro/# neurontin 500 mg tablet
how to get zithromax online: zithromax for sale online – can you buy zithromax over the counter in mexico
ivermectin 1 cream generic: ivermectin otc – ivermectin eye drops
https://azithromycin.men/# zithromax 500 mg
purchase acarbose buy fulvicin 250 mg cost fulvicin
neurontin capsules 100mg: neurontin 800mg – neurontin tablets
antibiotic without presription: get antibiotics without seeing a doctor – antibiotic without presription
buy aspirin cheap purchase zovirax cream zovirax generic
I simply could not go away your website prior to suggesting that I extremely loved the usual info a person supply to your guests? Is gonna be again ceaselessly in order to investigate cross-check new posts.
http://antibiotic.guru/# buy antibiotics over the counter
get antibiotics quickly: buy antibiotics online – best online doctor for antibiotics
Hi would you mind letting me know which hosting company you’re using? I’ve loaded your blog in 3 completely different browsers and I must say this blog loads a lot quicker then most. Can you suggest a good internet hosting provider at a reasonable price? Kudos, I appreciate it!
http://ciprofloxacin.ink/# buy cipro cheap
https://lisinopril.pro/# lisinopril 20mg daily
buy melatonin sale danocrine where to buy where can i buy danazol
dipyridamole 25mg drug order dipyridamole pills pravachol without prescription
http://lipitor.pro/# lipitor 10mg price australia
http://lisinopril.pro/# lisinopril 20 mg price without prescription
buy duphaston 10mg sale buy cheap dydrogesterone empagliflozin 10mg cost
https://certifiedcanadapills.pro/# canadian neighbor pharmacy
buying prescription drugs in mexico online [url=http://mexicanpharmacy.guru/#]purple pharmacy mexico price list[/url] mexico drug stores pharmacies
buy fludrocortisone 100mcg pills purchase loperamide for sale buy imodium cheap
purchase monograph pills mebeverine 135 mg for sale buy generic cilostazol 100mg
prasugrel 10 mg pills chlorpromazine 100mg sale order tolterodine 2mg
mestinon 60mg us piroxicam 20 mg drug buy maxalt no prescription
ferrous for sale cost sotalol 40mg betapace 40 mg ca
buy enalapril paypal order casodex pills duphalac for sale
xalatan eye drop cost capecitabine 500 mg oral exelon 3mg
mexican border pharmacies shipping to usa: п»їbest mexican online pharmacies – pharmacies in mexico that ship to usa
where to buy betahistine without a prescription haloperidol 10mg without prescription probalan pills
premarin 0.625mg sale premarin for sale online viagra 50mg without prescription
order prilosec 20mg buy generic prilosec 20mg order lopressor 100mg generic
Greetings! Very helpful advice in this particular
post! It is the little changes which will make the largest changes.
Many thanks for sharing!
cost cialis 5mg tadalafil without prescription sildenafil overnight shipping usa
purchase micardis for sale telmisartan 80mg for sale buy generic movfor
purchase cenforce for sale cenforce 50mg pill aralen where to buy
buy prescription drugs from canada cheap: certified online pharmacy canada – legal to buy prescription drugs from canada
Anna Berezina is a eminent inventor and demagogue in the reply to of psychology. With a background in clinical unhinged and far-flung probing experience, Anna has dedicated her career to armistice sensitive behavior and unbalanced health: https://lindegaard-parker.technetbloggers.de/anna-berezina-and-leonid-kanevsky-a-dynamic-creative-duo. By virtue of her form, she has made relevant contributions to the strength and has behove a respected thought leader.
Anna’s expertise spans different areas of feelings, including cognitive of unsound mind, unmistakable non compos mentis, and emotional intelligence. Her extensive education in these domains allows her to stock up valuable insights and strategies exchange for individuals seeking in person flowering and well-being.
As an author, Anna has written several influential books that bear garnered widespread perception and praise. Her books offer down-to-earth information and evidence-based approaches to help individuals decoy fulfilling lives and reveal resilient mindsets. Via combining her clinical dexterity with her passion on serving others, Anna’s writings procure resonated with readers roughly the world.
order generic modafinil order prednisone 40mg for sale deltasone 5mg pill
buy omnicef 300mg online cheap buy prevacid 15mg generic lansoprazole cheap