#include<iostream>
#include<cstring>
using namespace std;
const int MAX_N = 20;
const int BUF = 1 << MAX_N;


int N, K;

void read() {
    cin >> N >> K;
    --K;
}


int rec(bool decreased, int k, int mask, int dp[2][MAX_N][BUF]) {
    if (mask == (1 << N) - 1) {
        return decreased ? 1 : 0;
    }

    int &ret = dp[decreased][k][mask];
    if (ret != -1) return ret;

    ret = 0;
    
    for (int i = 0; i < N; ++i) {
        if (mask & (1 << i)) {
            continue;
        }
        if (decreased && i < k) {
            continue;
        }

        ret += rec(decreased | (i < k), i, mask | (1 << i), dp);
    }
    
    return ret;
}


void work() {
    static int dp[2][MAX_N][BUF];
    memset(dp, -1, sizeof(dp));

    cout << rec(0, K, 1 << K, dp) << endl;
}


int main() {
    read();
    work();
    return 0;
}