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

public class P4 {

	static String fir = "";
	static String sec = "";
	static PrintWriter out;

	public static void main (String [] args) throws IOException {

		Scanner sc = new Scanner(new FileReader("DATA4.txt"));                                               
		out = new PrintWriter(new BufferedWriter(new FileWriter("OUT4.txt")));


		for(int i=0;i<5;i++)
		{
			fir = sc.nextLine();
			sec = sc.nextLine();

			recur(fir, sec, "");
		}

		out.close();                               
		System.exit(0);                               
	}

	public static void recur(String fir, String sec, String output)
	{
		if (fir.equals("") && sec.equals(""))
		{
			out.println(output);
		}
		else
		{
			if (fir.startsWith("x.") && sec.startsWith("xx"))
			{
				recur(fir.substring(2), sec.substring(2), output+"A");
			}
			if (fir.startsWith("xx") && sec.startsWith("xx"))
			{
				recur(fir.substring(2), sec.substring(2), output+"B");
			}
			if (fir.startsWith("x.x") && sec.startsWith("xxx"))
			{
				recur(fir.substring(3), sec.substring(3), output+"C");
			}
			if (fir.startsWith("xx") && sec.startsWith(".x"))
			{
				recur(fir.substring(2), sec.substring(2), output+"D");
			}
			if (fir.startsWith("xxx") && sec.startsWith(".xx"))
			{
				recur(fir.substring(3), sec.substring(3), output+"E");
			}
		}
	}
}