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();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    static int[] LList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => int.Parse(ReadLine())).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        if (c[0] == c[2] && c[1] == c[3]) WriteLine(0);
        else if (c[0] == c[2] || c[1] == c[3] || Math.Abs(c[0] - c[2]) + Math.Abs(c[1] - c[3]) <= 3) WriteLine(1);
        else WriteLine(2);
    }
}