#include <stdio.h>
int kaijo (int x){
    if(x==1 || x==0){
        return x;
    }else{
        x=x*kaijo(x-1);
        return x;
    }
}
int bunshi(int n, int r){
    if(r==0){
        return 1;
    }else if(r==1){
        return n;
    }else{
        n=n*bunshi(n-1,r-1);
        return n;
    }
}
int main(){
    printf("%d",bunshi(5,2)/kaijo(2));
    printf("%d",bunshi(6,3)/kaijo(3));
    printf("%d",bunshi(7,4)/kaijo(4));
    return 0;
}