#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) 
{
    long i,j=1,sum=0;
    for(i=1;i<=k;i++)
    {
        if(i==k)
        {
            for(long x=0;x<k;x++,j=j+2)
                sum=sum+j;
        }
        else 
            for(long x=0;x<i;x++)
                j=j+2;
    }
    return sum;
}

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