#include <bits/stdc++.h>

using namespace std;

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

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