import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		String s = sc.nextLine().replace(" ","");
		String one = s.replace("?","1");
		String four = s.replace("?","4");
		

		
		String ans = "";
		if (one.charAt(0)<one.charAt(1)&&one.charAt(1)>one.charAt(2) || one.charAt(0)>one.charAt(1)&&one.charAt(1)<one.charAt(2)) ans += "1";
		if (four.charAt(0)<four.charAt(1)&&four.charAt(1)>four.charAt(2) || four.charAt(0)>four.charAt(1)&&four.charAt(1)<four.charAt(2)) ans += "4";
		
		System.out.println(ans);
		
	}
}