Description: Monocarp is participating in a programming contest, which features $$$26$$$ problems, named from 'A' to 'Z'. The problems are sorted by difficulty. Moreover, it's known that Monocarp can solve problem 'A' in $$$1$$$ minute, problem 'B' in $$$2$$$ minutes, ..., problem 'Z' in $$$26$$$ minutes. After the contest, you discovered his contest log — a string, consisting of uppercase Latin letters, such that the $$$i$$$-th letter tells which problem Monocarp was solving during the $$$i$$$-th minute of the contest. If Monocarp had spent enough time in total on a problem to solve it, he solved it. Note that Monocarp could have been thinking about a problem after solving it. Given Monocarp's contest log, calculate the number of problems he solved during the contest. Input Format: The first line contains a single integer $$$t$$$ ($$$1 \le t \le 100$$$) — the number of testcases. The first line of each testcase contains a single integer $$$n$$$ ($$$1 \le n \le 500$$$) — the duration of the contest, in minutes. The second line contains a string of length exactly $$$n$$$, consisting only of uppercase Latin letters, — Monocarp's contest log. Output Format: For each testcase, print a single integer — the number of problems Monocarp solved during the contest. Note: None