int main()
main() must return int. Not void, not bool, not float. int.
Just int, nothing but int, only int.
Some compilers accept void main(), but that is non-standard and
shouldn't be used. Instead use int main().
void main() // ← BAD; DO NOT DO THIS
{
...
}
int main() // ← GOOD
{
...
}
int main(int argc, char** argv) // ← GOOD
{
...
}
As to the specific return value, if you don't know what else to return just
say
return 0;