#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    long a=k*(k-1)+1;
    long sum=0;
    while(k--){
        sum=sum+a;
        a+=2;
    }
    return sum;
    // Return the sum of the elements of the k'th group.
}

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