#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;

ll N;

int main(){
    cin >> N;
    if(N==1) cout << 0 << endl;
    if(N%2==0) cout << (N*N*N+3*N*N+5*N-6)/6 << endl;
    else cout << (N*N*N+3*N*N+5*N-3)/6 << endl;
}