import java.util.*;

public class detaileddifferences {
	
	public static void main(String[] args) {
	
		Scanner stdin = new Scanner(System.in);
		int nC = stdin.nextInt();
		
		for (int loop=0; loop<nC; loop++) {
			char[] s = stdin.next().toCharArray();
			char[] t = stdin.next().toCharArray();
			System.out.println(new String(s));
			System.out.println(new String(t));
			for (int i=0; i<s.length; i++) {
				if (s[i] == t[i])
					System.out.print(".");
				else
					System.out.print("*");
			}
			System.out.println();
			System.out.println();
		}
	}
}