#include <bits/stdc++.h>

using namespace std;

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

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