#include <bits/stdc++.h>

using namespace std;

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

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