#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

ll n, k;
vector<bool> used;
ll ans = 0;

void dfs(ll bit, ll k, ll cnt = 0) {
    if ((bit == ((1LL << n) - 1)) && (cnt == 1)) {
        ans++;
        return;
    }
    rep(i, n) {
        if (used[i]) continue;
        ll v = (k > (i + 1)) ? 1 : 0;
        if ((v == 0) || ((v == 1) && (cnt == 0))) {
            used[i] = true;
            dfs(bit | (1LL << i), i + 1, cnt + v);
            used[i] = false;
        }
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    cin >> n >> k;
    used.resize(n, false);
    used[k - 1] = true;
    dfs(1LL << (k - 1), k);
    cout << ans << endl;
    return 0;
}