You're trying to declare main within the graph() function. C does not support nested functions so to fix this you have to move the declaration of main() to after the graph() function.
So what you're trying is this:
Code:
void graph()
{
// ...
int main(){
// ...
}
}
and the fix is this:
Code:
void graph()
{
// ...
}
int main(){
// ...
}
Use of correct indentation will help a lot. I strongly advise putting the code through a code beautifier.