CF1856A Tales of a Sort

Alphen has an array of positive integers $ a $ of length $ n $ . Alphen can perform the following operation: - For all $ i $ from $ 1 $ to $ n $ , replace $ a_i $ with $ \max(0, a_i - 1) $ . Alphen will perform the above operation until $ a $ is sorted, that is $ a $ satisfies $ a_1 \leq a_2 \leq \ldots \leq a_n $ . How many operations will Alphen perform? Under the constraints of the problem, it can be proven that Alphen will perform a finite number of operations.

Each test contains multiple test cases. The first line of input contains a single integer $ t $ ( $ 1 \le t \le 500 $ ) — the number of test cases. The description of the test cases follows. The first line of each test case contains a single integer $ n $ ( $ 2 \le n \le 50 $ ) — the length of the array $ a $ . The second line of each test case contains $ n $ integers $ a_1, a_2, \dots, a_n $ ( $ 1 \le a_i \le 10 ^ 9 $ ) — the elements of the array $ a $ .

For each test case, output a single integer — the number of operations that Alphen will perform.

In the first test case, we have $ a=[1,2,3] $ . Since $ a $ is already sorted, Alphen will not need to perform any operations. So, the answer is $ 0 $ . In the second test case, we have $ a=[2,1,2,1,2] $ . Since $ a $ is not initially sorted, Alphen will perform one operation to make $ a=[1,0,1,0,1] $ . After performing one operation, $ a $ is still not sorted, so Alphen will perform another operation to make $ a=[0,0,0,0,0] $ . Since $ a $ is sorted, Alphen will not perform any other operations. Since Alphen has performed two operations in total, the answer is $ 2 $ .