using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = long.Parse(ReadLine());
        WriteLine((n * 2 + 1) * (n * 2 + 1) / 2 + 1 + (n * 2 - 1) * (n * 2 - 1) / 2 + 1);
    }
}