B'You are given a string s consisting of n characters. These characters are among the first k lowercase letters of the Latin alphabet. You have to perform n operations with the string. During the i -th operation, you take the character that initially occupied the i -th position, and perform one of the following actions with it: For example, suppose the initial string is test, k = 20 , and the sequence of operations is URLD. Then the string is transformed as follows: The result of performing the sequence of operations is saes. Given the string s and the value of k , find the lexicographically smallest string that can be obtained after applying a sequence of operations to s . The first line contains one integer t ( 1 <= t <= 1000 ) -- the number of test cases. Each test case consists of two lines. The first line contains two integers n and k ( 1 <= n <= 500 ; 2 <= k <= 26 ). The second line contains a string s consisting of n characters. Each character is one of the k first letters of the Latin alphabet (in lower case). For each test case, print one line containing the lexicographically smallest string that can be obtained from s using one sequence of operations. '...