import java.util.Scanner;

public class HelloWorld {

	    public static void main(String[] args) throws Exception {

	    	Scanner sc = new Scanner(System.in);
	    	int[] xy_initial = new int[2];
	    	int[] xy_goal = new int[2];
	    	xy_initial[0] = sc.nextInt();
	    	xy_initial[1] = sc.nextInt();
	    	xy_goal[0] = sc.nextInt();
	    	xy_goal[0] = sc.nextInt();
	    	sc.close();


	    	if (Math.abs(xy_goal[0] - xy_initial[0]) +
	    		 Math.abs(xy_goal[1] - xy_initial[1]) > 3) {
	    		System.out.println(2);
	    	}else {
	    		System.out.println(1);
	    	}

	    	}

}