Alphabet Difference Problem Code: ALPDIFF Java Answer

  Code: Nium Challenge  » Alphabet Difference

Alphabet Difference 

Problem Code: ALPDIFF

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You are given two strings A and B containing small english alphabets ['a' - 'z']. You have to find the set of distinct characters that are present in string B but not in A. Print this set of characters sorted in increasing order in the form of a string. 

If there are no such characters that are present in B but not in A, then print -1.   

Note

You just need to print an alphabet once in the resultant string if its present in string B but not in string A.

Input

The first line of the input contains an integer T denoting the number of test cases. The description of T test cases follows.

First line of each testcase contains string A.

Second line of each testcase contains string B.

Output

For each test case, output a single line containing answer. 

Constraints

1 ≤ T ≤ 20

1 ≤ Length of string A , B ≤ 100000 

Information to Score Partial Points

For 5% of the score, it is guaranteed that Length of strings are  ≤ 26 and all alphabets in string B are distinct.

For 30% of the score, it is guaranteed that Length of strings are  ≤ 500.

For rest 65% of the score, original constraints are applicable.

Example
Input:

2

codechef

certification

teacher

cheater

Output:

ainrt

-1

Explanation

Test case 1: String A is "codechef" and string B is "certification". {'a','i','n','r','t'} are the characters present in string B but not in A.

Test case 2: String A is "teacher" and string B is "cheater". Since all the alphabet in string B are also present in string A, hence answer is -1.

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