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

int n;

int main(){
    cin>>n;
    unsigned long long s=0;
    for(int i=1;i<=n-3;i++){
        s+=(unsigned long long)i*(n-i-2);
    }
    unsigned long long res=n*s/4;
    cout<<res;
    return 0;
}