using System;

class Program
{
    static void Main()
    {
        var arr = Console.ReadLine().Trim().Split(' ');
        int a = int.Parse(arr[0]);
        int b = int.Parse(arr[1]);
        int c = int.Parse(arr[2]);
        int d = int.Parse(arr[3]);
        
        int ans;
        if (a == c || b == d)
        {
            ans = 1;
        }
        else if (Math.Abs(a - c) + Math.Abs(b - d) <= 3)
        {
            ans = 1;
        }
        else
        {
            ans = 2;
        }
        
        Console.WriteLine(ans);
    }
}