View Code of Problem 2591

/*


*/
#include <cstdio>
#include <string>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
	int t;
	cin>>t;
	while(t--){
		string s1,s2;
		cin>>s1>>s2;
		vector <char>my;
		for(int i=0;i<s1.size();i++)
		{
			for(int j=0;j<s2.size();j++){
				if(s1[i]==s2[j]&&s1[i]!='&'){
					my.push_back(s1[i]);
					s1[i]='&';
					s2[j]='&';
					
				}
			}
		}
		if(my.size()>0){
				sort(my.begin(),my.end());
				for(int i=0;i<my.size();i++){
					printf("%c",my[i]);
		}
			printf("\n");
		}else{
			printf("-1\n");
		}
	
		
	}
}