#include <algorithm>
#include <iostream>
#include <numeric>
#include <utility>
#include <vector>

int main() {
    using namespace std;
    int n, k;
    cin >> n >> k;
    vector<int> a(n);
    iota(a.begin(), a.end(), 1);
    swap(a[0], a[k - 1]);
    sort(a.begin() + 1, a.end());
    int ans = 0;
    do {
        if (a[0] != k) { break; }
        int d = 0;
        for (int i = 0; i < n - 1; i++) {
            if (a[i] > a[i + 1]) { d++; }
        }
        if (d == 1) { ans++; }
    } while (next_permutation(a.begin(), a.end()));
    cout << ans << endl;
}