import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int a = sc.nextInt(), b = sc.nextInt(), c = sc.nextInt(), d = sc.nextInt();
int min = Math.abs(a - b);
min = Math.min(Math.abs(a - c) + Math.abs(b - d), min);
min = Math.min(Math.abs(b - c) + Math.abs(a - d), min);
System.out.println(min);
}
}