C. K-Complete Wordtime limit per test2 secondsmemory limit per test512 megabytesinputstandard inputoutputstandard outputWord s of length n is called k-complete if   s is a palindrome, i.e. s_i=s_{n+1-i} for all 1 \le i \le n;  s has a period of k, i.e. s_i=s_{k+i} for all 1 \le i \le n-k. For example, "abaaba" is a 3-complete word, while "abccba" is not.Bob is given a word s of length n consisting of only lowercase Latin letters and an integer k, such that n is divisible by k. He wants to convert s to any k-complete word.To do this Bob can choose some i (1 \le i \le n) and replace the letter at position i with some other lowercase Latin letter.So now Bob wants to know the minimum number of letters he has to replace to convert s to any k-complete word.Note that Bob can do zero changes if the word s is already k-complete.You are required to answer t test cases independently.InputThe first line contains a single integer t (1 \le t\le 10^5) — the number of test cases.The first line of each test case contains two integers n and k (1 \le k < n \le 2 \cdot 10^5, n is divisible by k).The second line of each test case contains a word s of length n.It is guaranteed that word s only contains lowercase Latin letters. And it is guaranteed that the sum of n over all test cases will not exceed 2 \cdot 10^5.OutputFor each test case, output one integer, representing the minimum number of characters he has to replace to convert s to any k-complete word.ExampleInput
4
6 2
abaaba
6 3
abaaba
36 9
hippopotomonstrosesquippedaliophobia
21 7
wudixiaoxingxingheclp
Output
2
0
23
16
NoteIn the first test case, one optimal solution is aaaaaa.In the second test case, the given word itself is k-complete.
4
6 2
abaaba
6 3
abaaba
36 9
hippopotomonstrosesquippedaliophobia
21 7
wudixiaoxingxingheclp

2 0 23 16 
['dfs and similar', 'dsu', 'greedy', 'implementation', 'strings', '*1500']