B'You are given an array a consisting of n non-negative integers. It is guaranteed that a is sorted from small to large. For each operation, we generate a new array b_i=a_{i+1}-a_{i} for 1 <= i < n . Then we sort b from small to large, replace a with b , and decrease n by 1 . After performing n-1 operations, n becomes 1 . You need to output the only integer in array a (that is to say, you need to output a_1 ). The input consists of multiple test cases. The first line contains a single 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 one integer n ( 2 <= n <= 10^5 ) -- the length of the array a . The second line contains n integers a_1,a_2, ... ,a_n ( 0 <= a_1 <= ldots <= a_n <= 5 cdot 10^5 ) -- the array a . It is guaranteed that the sum of n over all test cases does not exceed 2.5 cdot 10^5 , and the sum of a_n over all test cases does not exceed 5 cdot 10^5 . For each test case, output the answer on a new line. To simplify the notes, let operatorname{sort}(a) denote the array you get by sorting a from small to large. In the first test case, a=[1,10,100] at first. After the first operation, a= operatorname{sort}([10-1,100-10])=[9,90] . After the second operation, a= operatorname{sort}([90-9])=[81] . In the second test case, a=[4,8,9,13] at first. After the first operation, a= operatorname{sort}([8-4,9-8,13-9])=[1,4,4] . After the second operation, a= operatorname{sort}([4-1,4-4])=[0,3] . After the last operation, a= operatorname{sort}([3-0])=[3] . '...