uva - 369

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <iostream>
#include <list>
#include <climits>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

using namespace std;

#define REP(i,n) for(__typeof(n) i=0; i<(n); i++)
#define FOR(i,a,b) for(__typeof(b) i=(a); i<=(b); i++)
#define RFOR(i,a,b) for(__typeof(b) i=(a); i>(b); i--)
typedef unsigned long long ui64;

#define Max 100
ui64 dp[Max+1][Max+1];

void _100C100() {
    dp[1][0] = 1;
    dp[1][1] = 1;

    FOR(i, 2, Max) {
        dp[i][0] = 1;
        for(int j = 1; j <= i; j++) {
            // nCr = (n-1)C(r-1) + (n-1)Cr
            dp[i][j] = dp[i-1][j-1] + dp[i-1][j];
        }
    }
}

int main() {
    int N, M;
    _100C100();
    while(cin>>N>>M) {
        if(!N && !M) break;
        printf("%d things taken %d at a time is %llu exactly.\n",N,M,dp[N][M]);
    }
    return 0;
}


/*
int main()
{
    //READ("input.txt");
    int N, M;
    vector <int> v;
    while(cin>>N>>M) {
        RFOR(i, N, (N-M)) v.pb(i);
        FOR(i, 2, M) {
            //

            //
        }

    }
    return 0;
}

*/