import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution 
{
    public static long calAns(long j , int k , int i)
    {
        if(k==i)
        {
            long ans=0;
            while(k>0)
            {
                ans = ans + j ;
                j = j-2;
                k--;
            }
            return ans;
        }
        else
        {
            i++;
            j = j + 2*i;
            return calAns( j ,  k ,  i);
        }
    }
    
    public static void main(String[] args) 
    {
        Scanner in = new Scanner(System.in);
        int k = in.nextInt();
        long n = 1000000;
        //long a[] = new long[1000000];
        
        long j=1;
        long ans =0;
        int i=1;
        /*for(int i=0 ; i<k ; i++)
        {
            int temp = i;
            ans=0;
            while(temp>=0)
            {
                ans = ans + j;
                j=j+2;
                temp--;
            }
        }*/
        
        ans =  calAns( j ,  k ,  i);
        
        System.out.println(ans);
        in.close();
    }
}