#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    long num =  k - 1;
    num = ((1+num)*num);
    num/=2;
    long x = num*2 + 1;
    long y = x + (k-1)*2;

    long ans = (x + y)*k;
    return ans/2;
}

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