#include <bits/stdc++.h>

using namespace std;

int main() {
    long long k,x,a,b;
    cin >> k;
    x = k*(k-1)/2;
    a = 2*x+1;
    b = 2*(x+k-1)+1;
    cout << ((b-a)/2+1) * (a+b) / 2;    
}