#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    // Return the sum of the elements of the k'th group.
    //1st element = k*k-k+1
    long sum=k*k-k+1;
    long term=k*k-k+1;
    for(int i=0;i<k-1;i++){
        sum+=term+2;
        term+=2;
    }
    return sum;
}

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