#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    long p = 1 ,s = 0,sum=0;
    for(long i=1;i<=k;i++) s += i;
    for(long i=1;i<s;i++) p+=2;
    for(long i=0;i<k;i++){
        sum += p;
        p -= 2;
    }
    return sum;
}

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