n = int(input())
print(n * (n-1) * (n-2) * (n-3) // 24 if n >= 4 else 0)

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