#include <bits/stdc++.h>

using namespace std;

int main() {
    long long int k, first =1,sum=0;
    cin >> k;
    
    for(long int i=0; i<k;i++)
    {
        first = first + 2*i;
    }
    
    for(long int i=0; i<k;i++)
    {
        sum =sum+first;
        first = first+2;
    }
    
    cout<<sum;
    return 0;
}