Return type of main function?

Question

Is it necessary to have return type of main function as int (and not void)? Why does the code show a compilation error?
https://code.sololearn.com/czUK2qE6vJyq/?ref=app
https://code.sololearn.com/czUK2qE6vJyq/?ref=app

Answer 1

if the code returns a 0, it means the code compiled succesfully and if it returns a -1 it means the code had a error, and if the main is a void it cant give a return value.

correct me if im wrong

Answer 2

In C++, returning an integer from the main function is necessary.