using System.Numerics;

public class Program
{
    public static void Main()
    {

        //BigInteger num = BigInteger.Parse(Console.ReadLine() ?? string.Empty);
        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        string[] moji = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;


        BigInteger a = BigInteger.Parse(moji[0]);
        BigInteger b = BigInteger.Parse(moji[1]);
        BigInteger c = BigInteger.Parse(moji[2]);
        BigInteger d = BigInteger.Parse(moji[3]);


        if (a == c || b == d)
        {
            Console.WriteLine(1);
        }
        else if (a - 2 <= c && c <= a && b - 2 <= d&&d<=b || a - 2 <= c &&c <=a&& b + 2 >= d && d >= b ||
            a + 2 >= c && c >= a && b - 2 <= d && d <= b || a + 2 >= c && c >= a && b + 2 >= d && d >= b)
        {
            Console.WriteLine(1);
        }
        else
        {
            Console.WriteLine(2);
        }
        //a!=c&&b!= d==console.writeline(2);
    }
}