POJ 1942组合数

#include<cstdio>
using namespace std;
typedef long long ll;
ll C(ll n,ll m)
{
	if(m>n-m)
	{
		m=n-m;
	}
	ll ret=1;
	ll i;
	for(i=1;i<=m;i++)
	{
		ret=ret*(n-i+1)/i;
	}
	return ret;
}

int main()
{
	ll n,m;
	while(~scanf("%lld%lld",&n,&m))
	{
		if(n+m==0)
		{
			break;
		}
		printf("%lld\n",C(n+m,n));
	}
}