CF2166A Same Difference

You are given a string $ s $ of length $ n $ , consisting of lowercase letters. In one operation, you can select an integer $ i $ such that $ 1\leq i < n $ and change $ s_i $ into $ s_{i+1} $ . What is the minimum number of operations needed to make every character the same? It can be proved that this is always possible.

Each test contains multiple test cases. The first line contains the number of test cases $ t $ ( $ 1 \le t \le 20 $ ). The description of the test cases follows. The first line of each test case contains an integer $ n $ ( $ 2\le n\le 100 $ ) — the length of the string. The following line contains a string $ s $ of length $ n $ , consisting of lowercase letters. It is guaranteed that the sum of $ n $ over all test cases does not exceed $ 100 $ .

For each test case, output a single integer — the minimum number of operations needed to make every character the same.

In the first test case, you can change $ s_2 $ to $ s_3 $ using $ 1 $ operation to reach the goal. In the third test case, you can change $ s_3 $ to $ s_4 $ and then change $ s_2 $ to $ s_3 $ , using $ 2 $ operations in total. It can be proved that the answer is not less than $ 2 $ .