B'You are given an array a[0 ldots n - 1] = [a_0, a_1, ldots, a_{n - 1}] of zeroes and ones only. Note that in this problem, unlike the others, the array indexes are numbered from zero, not from one. In one step, the array a is replaced by another array of length n according to the following rules: It means that the whole array a^{ rightarrow d} can be represented as a sequence a^{ rightarrow d} = [a_{n - d}, a_{n - d + 1}, ldots, a_{n - 1}, a_0, a_1, ldots, a_{n - d - 1}] For example, if a = [0, 0, 1, 1] and d = 1 , then a^{ rightarrow d} = [1, 0, 0, 1] and the value of a after the first step will be [0 , & , 1, 0 , & , 0, 1 , & , 0, 1 , & , 1] , that is [0, 0, 0, 1] . The process ends when the array stops changing. For a given array a , determine whether it will consist of only zeros at the end of the process. If yes, also find the number of steps the process will take before it finishes. The first line contains an integer t ( 1 <= q t <= q 1000 ) -- the number of test cases. The next 2t lines contain descriptions of the test cases. The first line of each test case description contains two integers: n ( 1 <= n <= 10^6 ) -- array size and d ( 1 <= d <= n ) -- cyclic shift offset. The second line of the description contains n space-separated integers a_i ( 0 <= a_i <= 1 ) -- elements of the array. It is guaranteed that the sum of n over all test cases does not exceed 10^6 . Print t lines, each line containing the answer to the corresponding test case. The answer to a test case should be a single integer -- the number of steps after which the array will contain only zeros for the first time. If there are still elements equal to 1 in the array after the end of the process, print -1. In the third sample test case the array will change as follows: In the fourth sample test case, the arr'...