#include <bits/stdc++.h>

using namespace std;

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

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