#include <iostream>
using namespace std;

// Source: OIS

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