using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;

class Solution {

    static BigInteger sumOfGroup(BigInteger k)
	{
		BigInteger n = ((k) * (k - 1)) + 1;
		BigInteger x = (k) * (k - 1);
		return (n * k) + x;
	}

	static void Main(String[] args)
	{
		int k = Convert.ToInt32(Console.ReadLine());
		BigInteger answer = sumOfGroup(k);
		Console.WriteLine(answer);
	}
}