#include <iostream>
using namespace std;
long long ans[] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800, 87178291200, 1307674368000, 20922789888000, 355687428096000, 6402373705728000, 121645100408832000, 2432902008176640000};
int main() {
    int n; cin >> n;
    cout << ans[n] << endl;
    return 0;
}