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

    static long sumOfGroup(int k) {
        var array = new List<long>();
        
        for(var i = k * 2; i <= k * k + 2; i++) {
            if (i % 2 != 0) array.Add(i);
        }

        var result = 0L;
        for(var i = 0; i < array.Count; i++) {
            result += array[i];
        }
        
        return result;
    }

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