#include <iostream>

using namespace std;

int main (){

    int n,i,j,br;

    br=0;


    cin >> n;

    for ( i=0; i<=n; i++ ){

        for ( j=i; j<=n; j++ ){

            br=br+i+j;

            }

        }

    cout << br << endl;

    return 0;

    }