#include <bits/stdc++.h>

using namespace std;
long computeK(int n){
    return (long)n*(n+1)*.5;
}

long sumOfGroup(int n) {
    long k1 = computeK(n);
    long k2 = computeK(n-1);


    return k1*k1-k2*k2;
    
}

int main() {
    int n;
    cin >> n;
    long answer = sumOfGroup(n);
    cout << answer << endl;
    return 0;
}