Paths on a Grid(poj 1942)

//注意循环的时候，要循环小的数，否则会超时
#include<cstdio>
#include<iostream>
#define LL long long
using namespace std;
int main()
{
while(1)
{
LL a,b,ans=1;
cin>>a>>b;
if(a==0&&b==0)break;
LL m=a+b;
b=min(a,b);
for(LL i=1;i<=b;i++)
{
ans*=(m-(i-1));
ans/=i;
}
cout<<ans<<endl;
}
return 0;
}