#include <bits/stdc++.h>

using namespace std;

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

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