#include <stdio.h>

int factorial (int num)
{

    if (num ==0){
        return  1;
    }
    else{
        return  num * factorial(num-1);
    }
}

int maneras_dif (int n,int r)
{
    int man;

    man = factorial(n) * (factorial(r) * (factorial(n-r)));
    return man;
}

int main()
{
    int n, r,dif_maner;

    printf("Ingrese n y r \n");
    scanf("%d %d",&n,&r);
    dif_maner = maneras_dif(n,r);
    printf("%d",dif_maner);
    return 0;
}