B'You are given a sequence a_1, a_2, ldots, a_n . Each element of a is 1 or 2 . Find out if an integer k exists so that the following conditions are met. If there exist multiple k that satisfy the given condition, print the smallest. Each test contains multiple test cases. The first line contains the number of test cases t ( 1 <= t <= 100 ). Description of the test cases follows. The first line of each test case contains one integer n ( 2 <= q n <= q 1000 ). The second line of each test case contains n integers a_1, a_2, ldots, a_n ( 1 <= q a_i <= q 2 ). For each test case, if there is no such k , print -1 . Otherwise, print the smallest possible k . For the first test case, k=2 satisfies the condition since a_1 cdot a_2 = a_3 cdot a_4 cdot a_5 cdot a_6 = 4 . k=3 also satisfies the given condition, but the smallest should be printed. For the second test case, there is no k that satisfies a_1 cdot a_2 cdot ldots cdot a_k = a_{k+1} cdot a_{k+2} cdot ldots cdot a_n For the third test case, k=1 , 2 , and 3 satisfy the given condition, so the answer is 1 . '...