import java.io.*;
import java.util.*;
import java.awt.geom.Point2D;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;

public class Main {
    public static void main(String[] args){
        // TODO 自動生成されたメソッド・スタブ
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int y = sc.nextInt();
        int x1 = sc.nextInt();
        int y1 = sc.nextInt();
        if(x!=y){
        	System.out.println(Math.max(x, y));
        }else{
        	if( x1==y1 &&( (x1>0 && x>x1)|| (x1<0 && x1>x) )){
        		System.out.println(Math.max(x, y)+1);
        	}else{
        		System.out.println(Math.max(x, y));
        	}
        }
    }
}