using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static long sumOfGroup(long k) {
        long beginN = k*(k-1)/2+1;
        long endN = (k+1)*k/2;
        
        long beginValue = 2*beginN - 1;
        long endValue = 2*endN - 1;
        
        long result = 0;
        
        //Console.WriteLine(beginValue*(endN-beginN+1));
        
        result += beginValue*(endN-beginN+1);
        
        //Console.WriteLine(beginN);
        //Console.WriteLine(endN);
        //Console.WriteLine((endN-beginN)*(endN-beginN+1));
        
        result += (endN-beginN)*(endN-beginN+1);
        
        return result;
    }

    static void Main(String[] args) {
        long k = Convert.ToInt64(Console.ReadLine());
        long answer = sumOfGroup(k);
        Console.WriteLine(answer);
    }
}