#include<bits/stdc++.h>
using namespace std;
long long n,as;
int main() {
    cin >> n;
    as = n * (n - 1) / 2 * (n - 2) / 3 * (n - 3) / 4;
    cout << as << endl;
    return 0;
}

这里只得了82分 WA了两个点