#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    // Return the sum of the elements of the k'th group.
    //numbers already gone 
    long gone = k*(k-1)+1;
    long sum =0; 
    sum = gone*k+k*(k-1);
    return sum;
    
    
}

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