text: #include <bits/stdc++.h>
  #define ll long long int
  using namespace std;
  ll n[102][102];
  ll fnc(int a, int b){
      if(a == b) return 1;
      if(b == 1) return a;
      if(n[a][b] == 0){
          n[a][b] = fnc(a - 1, b) + fnc(a - 1, b - 1);
      }
      return n[a][b];
  }
  int main(){
      ll a, b;
      while(scanf("%lld %lld", &a, &b) != EOF && a && b) printf("%lld things taken %lld at a time is %lld exactly.\n", a, b, fnc(a, b));
      return 0;
  }
  