View Code of Problem 2591

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner=new Scanner(System.in);
		int t=Integer.parseInt(scanner.next());
		while(t-->0) {
			String s1=scanner.next();
			String s2=scanner.next();
			char[] c1=s1.toCharArray();
			char[] c2=s2.toCharArray();
			List<Character> ans=new ArrayList<>();
			for(int i=0;i<c1.length;i++) {
				for(int j=0;j<c2.length;j++) {
					if(c1[i]==c2[j]) {
						ans.add(c1[i]);
						c2[j]='0';
						c1[i]='1';
					}
				}
			}
			Collections.sort(ans);
			if(ans.size()==0) {
				System.out.println(-1);
			}
			else {
				for(char c:ans) {
					System.out.print(c);
				}
				System.out.println();
			}
		}
	}

}