#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    if (k == 1) return 1;
    
    long sum = 0L;
    long odd = 1L;
    
    long i, j;
    
    for (i = 2; i < k; i++) {
        for (j = 0; j < i; j++) odd += 2L;
    }
    
    odd += 2L;
    
    for (i = 0; i < k; i++) {
        sum += odd;
        
        odd += 2L;
    }
    
    return sum;
}

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