#include <bits/stdc++.h>

using namespace std;

long long int sumOfGroup(long long int k) {
    long long int x=k*(k-1)+1,sum=0;
    for(long long int i=x;i<x+(2*k);i+=2)
    {
        sum+=i;
    }
    return sum;
}

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