#include <iostream>
#include <bits/stdc++.h>
 
#define ll long long
#define lp(n) for(int  i= 0 ; i< (n) ; i++)
//#define all(v) (v.begin()), ((v.end()))
//#define sz(v)   ((int)((v).size()))
//#define endl '\n'
//#define all(v) ((v).begin()), ((v).end())
//#define sz(v) ((int)((v).size()))
using namespace std;
 
//typedef vector<char> vi;
int cnt=0;
 
ll ordinary(int n){
    if(n==1)
        return n;
    return n*ordinary(n-1);
}
 
ll factorial(int n,int m){
    if(n==m+1)
        return n;
    return n*factorial(n-1,m);
}
int main(){
    int n,m;
    while(cin>>n>>m){
    if(m==0&&n==0)
        break;
    ll b = max(n-m,m);
    cout<<n<< " things taken "<<m<<" at a time is "<<factorial(n,b)/ordinary(n-b)<<" exactly.";
    cout<<endl;
    }
 
}
 

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