B'Given an array of n positive integers a_1, a_2, ... , a_n ( 1 <= a_i <= 1000 ). Find the maximum value of i + j such that a_i and a_j are coprime, ^{ dagger} or -1 if no such i , j exist. For example consider the array [1, 3, 5, 2, 4, 7, 7] . The maximum value of i + j that can be obtained is 5 + 7 , since a_5 = 4 and a_7 = 7 are coprime. ^{ dagger} Two integers p and q are coprime if the only positive integer that is a divisor of both of them is 1 (that is, their greatest common divisor is 1 ). The input consists of multiple test cases. The first line contains an integer t ( 1 <= q t <= q 10 ) -- the number of test cases. The description of the test cases follows. The first line of each test case contains an integer n ( 2 <= q n <= q 2 cdot10^5 ) -- the length of the array. The following line contains n space-separated positive integers a_1 , a_2 ,..., a_n ( 1 <= q a_i <= q 1000 ) -- the elements of the array. It is guaranteed that the sum of n over all test cases does not exceed 2 cdot10^5 . For each test case, output a single integer -- the maximum value of i + j such that i and j satisfy the condition that a_i and a_j are coprime, or output -1 in case no i , j satisfy the condition. For the first test case, we can choose i = j = 3 , with sum of indices equal to 6 , since 1 and 1 are coprime. For the second test case, we can choose i = 7 and j = 5 , with sum of indices equal to 7 + 5 = 12 , since 7 and 4 are coprime. '...