What are the top 5 installed free apps?
free app refers to price = 0; most installed app refers to MAX(Installs);
SELECT App FROM playstore WHERE Price = 0 ORDER BY CAST(REPLACE(REPLACE(Installs, ',', ''), '+', '') AS INTEGER) DESC LIMIT 5
database name:db_id app_store
googleplaystore table googleplaystore Cols: App dtype text, Category dtype text, Rating dtype real, Reviews dtype integer, Size dtype text, Installs dtype text, Type dtype text, Price dtype text, Content Rating dtype text, Genres dtype text, 
googleplaystore_user_reviews table googleplaystore_user_reviews Cols: App dtype text, Translated_Review dtype text, Sentiment dtype text, Sentiment Polarity dtype text, Sentiment Subjectivity dtype text, 
