import java.io.BufferedReader;
import java.io.FileReader;
import java.io.PrintWriter;
public class solution4 {
	static String out;
	static String A = "x.xx";
	static String B = "xxxx";
	static String C = "x.xxxx";
	static String D = "xx.x";
	static String E = "xxx.xx";
	static String input []=new String [2]; 
	public static void main (String args []) throws Exception{
		BufferedReader r = new BufferedReader (new FileReader("DATA4.txt"));
		PrintWriter p = new PrintWriter ("OUT4.txt");
		for (int i = 0; i < 5; i++){
			input [0]=r.readLine();
			input [1]=r.readLine();
			out = "ZZZZ";
			recurse (0, "");
			p.println(out);
		}
		p.close();
	}
	public static void recurse (int current, String test){
		if (!out.equals( "ZZZZ")){
			return;
		}
		if (current == input[0].length()){
			out = test;
		}
		if (current > input[0].length()-2){
			return;
		}
		
		String one = input[0].substring(current, current+2)+ input[1].substring(current, current+2);
		String two;
		if (current > input[0].length()-3){
			two = "";
		}else{
			two = input[0].substring(current, current+3)+ input[1].substring(current, current+3);
		}
		if (one.equals( A)){
			recurse (current+2, test+"A");
		}if (one.equals( B)){
			recurse (current+2, test+"B");
		} if (two.equals( C)){
			recurse (current+3, test+"C");
		} if (one.equals( D)){
			recurse (current+3, test+"D");
		} if (two.equals( E)){
			recurse (current+2, test+"E");
		}

		
	}
}