import java.util.Scanner;

public class Main {

	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		int x = scanner.nextInt();
		int y = scanner.nextInt();
		int x2 = scanner.nextInt();
		int y2=scanner.nextInt();
		if(x==y&&x2==y2&&x>x2) {
			System.out.println(Math.max(x, y)+1);
		}else {
			System.out.println(Math.max(x, y));
		}
	}
}