#include <bits/stdc++.h>
#define ll long long
using namespace std;

ll sumOfGroup(ll k) {
    // Return the sum of the elements of the k'th group.
      ll i,j,po = 1, sum = 0,sp;
      sp = k * (k - 1) + 1;
        for(j = sp; j < sp + (2*k); j+=2){
            sum += j;
        }
    return sum;
}

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