#include <bits/stdc++.h>

using namespace std;

long long sumOfGroup(long long k) {
    // Return the sum of the elements of the k'th group.
    long long s,c,t=(k*k)-k+1;
    s=0;c=0;
    while(c<k)
    {
         s=s+t;
        t+=2;
        c++;
    }
     return s;
}

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