You are given a string \(S\) that represents a number. This string consists of the following characters only:

• \(1\)
• \(2\)
• \(3\)

You can perform the following operation:

• Swap any two adjacent characters only if the absolute difference between the characters is \(1\)

Your task is to determine the smallest number that can be formed by using the provided operation. You can perform this operation any number of times (possibly zero). 

Note: Assume \(1\) based indexing.

Input format

• The first line contains an integer \(T\) that denotes the number of test cases.
• For each test case:
  • The first line contains an integer that denotes the length of string \(S\).
  • The second line contains a string that denotes the string \(S\).

Output format

For each test case, print a string representing the smallest number that can be formed in a new line.

Constraints

\(1 \le T \le 10 \\ 1 \le |S| \le 10^5 \)