A string s of length n, consisting of lowercase letters of the English alphabet, is given.

You must choose some number k between 0 and n. Then, you select k characters of s and permute them however you want. In this process, the positions of the other n-k characters remain unchanged. You have to perform this operation exactly once.

For example, if s="andrea", you can choose the k=4 characters "a_d_ea" and permute them into "d_e_aa" so that after the operation the string becomes "dneraa".

Determine the minimum k so that it is possible to sort s alphabetically (that is, after the operation its characters appear in alphabetical order).

Input

The first line contains a single integer t (1 ≤ t ≤ 1000) — the number of test cases. Then t test cases follow.

The first line of each test case contains one integer n (1 ≤ n ≤ 40) — the length of the string.

The second line of each test case contains the string s. It is guaranteed that s contains only lowercase letters of the English alphabet.

Output

For each test case, output the minimum k that allows you to obtain a string sorted alphabetically, through the operation described above.

Example

Input


4
3
lol
10
codeforces
5
aaaaa
4
dcba


Output


2
6
0
4

Note

In the first test case, we can choose the k=2 characters "_ol" and rearrange them as "_lo" (so the resulting string is "llo"). It is not possible to sort the string choosing strictly less than 2 characters.

In the second test case, one possible way to sort s is to consider the k=6 characters "_o__force_" and rearrange them as "_c__efoor_" (so the resulting string is "ccdeefoors"). One can show that it is not possible to sort the string choosing strictly less than 6 characters.

In the third test case, string s is already sorted (so we can choose k=0 characters).

In the fourth test case, we can choose all k=4 characters "dcba" and reverse the whole string (so the resulting string is "abcd").
num_lines = int(input())

def solve(string):
    unique_i = 0
    i = 0
    prev = []
    while i < len(string):
        j = i + 1
        min_j = string[i]
        min_j_ind = i
        while j < len(string):
            if string[j] < min_j:
                min_j = string[j]
                min_j_ind = j
            j += 1
        if min_j_ind != i:
            if i not in prev and min_j_ind not in prev:
                unique_i += 2
                prev.append(i)
                prev.append(min_j_ind)
            elif i not in prev:
                unique_i += 1
                prev.append(i)
            elif min_j_ind not in prev:
                unique_i += 1
                prev.append(min_j_ind)
            tmp = string[i]
            string[i] = string[min_j_ind]
            string[min_j_ind] = tmp
        i += 1
    return unique_i
    

i = 0
while i < num_lines:
    n = int(input())
    string = list(input())
    print(solve(string))
    i+=1