import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long a = sc.nextInt();
        long b = sc.nextInt();
        long c = sc.nextInt();
        long d = sc.nextInt();
        if (Math.abs(a - c) + Math.abs(b - d) <= 3) {
            System.out.println(1);
        } else if (a == c || b == d) {
            System.out.println(1);
        } else {
            System.out.println(2); 
        }
    }
}