Sjecista Solution:

#include <bits/stdc++.h>
using namespace std;

int main(){
    // #ifndef TESTING
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    // #endif

    int n;
    cin >> n;
    cout << (n * (n - 1) * (n - 2) * (n - 3)) / 24 << endl;
    
    return 0;
}