B'You are given a binary string s of length n , consisting of zeros and ones. You can perform the following operation exactly once: For example, if you apply the operation to the string 110001100110 with p=3 , after the second step, the string will become 011001100110, and after the third step, it will become 001100110011. A string s is called k -proper if two conditions are met: For example, with k=3 , the strings 000, 111000111, and 111000 are k -proper, while the strings 000000, 001100, and 1110000 are not. You are given an integer k , which is a divisor of n . Find an integer p ( 1 <= p <= n ) such that after performing the operation, the string s becomes k -proper, or determine that it is impossible. Note that if the string is initially k -proper, you still need to apply exactly one operation to it. Each test consists of multiple test cases. The first line contains one integer t ( 1 <= t <= 10^4 ) -- the number of test cases. The description of the test cases follows. The first line of each test case contains two integers n and k ( 1 <= k <= n , 2 <= n <= 10^5 ) -- the length of the string s and the value of k . It is guaranteed that k is a divisor of n . The second line of each test case contains a binary string s of length n , consisting of the characters 0 and 1. It is guaranteed that the sum of n over all test cases does not exceed 2 cdot 10^5 . For each test case, output a single integer -- the value of p to make the string k -proper, or -1 if it is impossible. If there are multiple solutions, output any of them. In the first test case, if you apply the operation with p=3 , after the second step of the operation, the string becomes 11100001, and after the third step, it becomes 00001111. This string is 4 -proper. In the second test case, it can be shown that the'...