If I recite this du'a 3 times are all my major and minor sins forgiven?

If I read Astagfiru-l-Laaha-l Azim allazi la ilaaha illa huw al-haiy al-Qaiyyum wa attubu ilayhi 3 times, are all my sins major sins and minor sins forgiven? And shirk too because I have commited shirk before, and if not how to repent from all those sins.