Which is the right way?

[sail3005]

After a recent programming test, that my friend got back, my teacher counted his code wrong because he used this:

int main()
{
//code here
return 0;
}

instead of

void main()
{
//code here
}

My friend tried to argue that the int way was better, and more standard, but the teacher said no. What do you guys have to say to this? Which is better?