B'There was a string s which was supposed to be encrypted. For this reason, all 26 lowercase English letters were arranged in a circle in some order, afterwards, each letter in s was replaced with the one that follows in clockwise order, in that way the string t was obtained. You are given a string t . Determine the lexicographically smallest string s that could be a prototype of the given string t . A string a is lexicographically smaller than a string b of the same length if and only if: The first line of the input contains a single integer t ( 1 <= t <= 3 cdot 10^4 ) -- the number of test cases. The description of test cases follows. The first line of each test case contains one integer n ( 1 <= n <= 10^5 ) -- the length of the string t . The next line contains the string t of the length n , containing lowercase English letters. It is guaranteed that the sum of n over all test cases doesn 't exceed 2 cdot 10^5 . For each test case, output a single line containing the lexicographically smallest string s which could be a prototype of t . In the first test case, we couldn 't have the string "a", since the letter a would transit to itself. Lexicographically the second string "b" is suitable as an answer. In the second test case, the string "aa" is not suitable, since a would transit to itself. "ab" is not suitable, since the circle would be closed with 2 letters, but it must contain all 26 . The next string "ac" is suitable. Below you can see the schemes for the first three test cases. The non-involved letters are skipped, they can be arbitrary placed in the gaps. '...