算法错误

> #include<iostream>
> using namespace std;
> int main()
> {
> 	int a,b;
> 	while(cin>>a>>b)
> 	{
> 		if(a==0&&b==0)return 0;
> 		if(a==b)cout<<"Stan wins\n";
> 		else{
> 		if(a<b)swap(a,b);
> 		int num=0;
> 		while(a<(2*b))
> 		{
> 			b=a-b;a=a-b;num++;
> 		}
> 		if(num%2==0)cout<<"Stan wins\n";
> 		else cout<<"Ollie wins\n";}
> 	}
> 	return 0;
> }