UVa 369 Combinations Solution

#include<iostream>
using namespace std;
int main()
{
    unsigned long long m,n,i,j,cnt,ans,s,l,m1,n1;
    while(cin>>n>>m)
    {
      if(n==0 && m==0)
      return 0;
      if(m>(n-m))
      s=n-m;
      else
      s=m;
      n1=m1=1;
      for(i=0;i<s;i++)
      {
          n1*=(n-i); //cout<<(n-i)<<" ";
          m1*=(i+1);
          for(j=m1;j>1;j--)
          if(m1%j==0)
          if(n1%j==0)
          {
              n1/=j;
              m1/=j;
          }
      }
      //cout<<n1<<" "<<m1<<endl;
      cout<<n<<" things taken "<<m<<" at a time is "<<n1<<" exactly."<<endl;
    }
}