B"You have 2n integers 1, 2, ... , 2n . You have to redistribute these 2n elements into n pairs. After that, you choose x pairs and take minimum elements from them, and from the other n - x pairs, you take maximum elements. Your goal is to obtain the set of numbers {b_1, b_2, ... , b_n } as the result of taking elements from the pairs. What is the number of different x -s ( 0 <= x <= n ) such that it's possible to obtain the set b if for each x you can choose how to distribute numbers into pairs and from which x pairs choose minimum elements? The first line contains a single integer t ( 1 <= t <= 1000 ) -- the number of test cases. The first line of each test case contains the integer n ( 1 <= n <= 2 cdot 10^5 ). The second line of each test case contains n integers b_1, b_2, ... , b_n ( 1 <= b_1 < b_2 < ... < b_n <= 2n ) -- the set you'd like to get. It's guaranteed that the sum of n over test cases doesn't exceed 2 cdot 10^5 . For each test case, print one number -- the number of different x -s such that it's possible to obtain the set b . In the first test case, x = 1 is the only option: you have one pair (1, 2) and choose the minimum from this pair. In the second test case, there are three possible x -s. If x = 1 , then you can form the following pairs: (1, 6) , (2, 4) , (3, 5) , (7, 9) , (8, 10) . You can take minimum from (1, 6) (equal to 1 ) and the maximum elements from all other pairs to get set b . If x = 2 , you can form pairs (1, 2) , (3, 4) , (5, 6) , (7, 9) , (8, 10) and take the minimum elements from (1, 2) , (5, 6) and the maximum elements from the other pairs. If x = 3 , you can form pairs (1, 3) , (4, 6) , (5, 7) , (2, 9) , (8, 10) and take the minimum elements f"...