B'You are given a string s of lowercase Latin letters. The following operation can be used: And you are given the integer k -- the maximum number of operations that can be performed. Find the minimum lexicographically possible string that can be obtained by performing no more than k operations. The string a=a_1a_2 ... a_n is lexicographically smaller than the string b = b_1b_2 ... b_n if there exists an index k ( 1 <= k <= n ) such that a_1=b_1 , a_2=b_2 , ..., a_{k-1}=b_{k-1} , but a_k < b_k . The first line contains a single integer t ( 1 <= t <= 10^4 ) --the number of test cases in the test. This is followed by descriptions of the test cases. The first line of each test case contains two integers n and k ( 1 <= n <= 2 cdot 10^5 , 1 <= k <= 10^9 ) -- the size of the string s and the maximum number of operations that can be performed on the string s . The second line of each test case contains a string s of length n consisting of lowercase Latin letters. It is guaranteed that the sum n over all test cases does not exceed 2 cdot 10^5 . For each test case, output the lexicographically minimal string that can be obtained from the string s by performing no more than k operations. '...