#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <map>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <algorithm>
#include <array>
#include <unordered_set>
#include <unordered_map>
#include <string>
using namespace std;

bool rcmp(int a, int b) { return a>b; }
typedef long long LL;



LL ft[32];
LL cc[16][16];
int main() {
    int n, i, j, m;
    scanf("%d %d", &n, &m);
    cc[0][0]=1; for (j=1; j<=n; j++) cc[0][j]=0;
    for (i=1; i<=n; i++) {
        for (j=i+1; j<=n; j++) cc[i][j]=0;
        cc[i][0]=0;
        for (j=1; j<=i; j++) {
            cc[i][j]=j*cc[i-1][j]+cc[i-1][j-1];
        }
        // for (j=1; j<=i; j++) printf("%d:%d => %lld\n", i, j, cc[i][j]);
    }
    ft[0]=1; for (i=1; i<=n; i++) ft[i]=ft[i-1]*i;
    for (i=1; i<=n; i++) {
        for (j=1; j<=i; j++) {
            cc[i][j]*=ft[j];
        }
    }
    if (m>n) printf("0\n");
    else printf("%lld\n", cc[n][m]);
    return 0;
}