#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>

const int N = 20;
ll C[N + 1][N + 1];
void init() {
    C[0][0] = 1;
    for (int i = 1; i <= N; i++) {
        C[i][0] = 1;
        for (int j = 1; j <= i; j++) {
            C[i][j] = C[i - 1][j] + C[i - 1][j - 1];
        }
    }
}
void solve() {
    int n;
    cin >> n;

    vector<ll> f(n + 1, 1);
    for (int i = 1; i <= n; i++) {
        f[i] = f[i - 1] * i;
    }

    ll res = f[n];
    for (int c = 1; c <= n; c++) {
        res -= (c % 2 == 1 ? 1 : -1) * C[n][c] * f[n - c];
    }
    cout << res << '\n';
}
signed main() {
    ios::sync_with_stdio(0); cin.tie(0);
    init();
    int t = 1;
    // cin >> t;
    while (t--) solve();
    return 0;
}
/*
g++ -std=c++17 1.cpp -o 1 && 1 < in.txt > out.txt
g++ -std=c++17 1.cpp -o 1 && ./1 < in.txt > out.txt

*/