import java.util.*;
public class Osho{
	public static void main(String... args){
		Scanner scan = new Scanner(System.in);
		int x=scan.nextInt(),y=scan.nextInt(),x1=scan.nextInt(),y1=scan.nextInt();
	}
	public static int count(int x,int y,int x1,int y1){
		int res = x+y-Math.min(x,y);
		if(x==y && x1==y1 && x1 < x && y1 < y){
			res++;
		}
		return res;
	}
}