import java.util.*;
import java.io.*;
import java.math.*;

public class No293 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String b = sc.next();
		String aa = a.replace('4', '8');
		String bb = b.replace('4', '8');
		if(Integer.parseInt(aa) > Integer.parseInt(bb)) System.out.println(a);
		else System.out.println(b);
	}
}