I came to know about the opportunity through https://careers.google.com/jobs/results/ Google’s website. Applied for the same with my resume. After two weeks got a mail Invite participating in the coding round. The mail had a unique ID and got the passkey(for login) on the day of the coding round1 (29th Aug 2020). The slot was open from 15:00 to 17:00 IST.

A coding round was conducted on the HackerEarth platform. The test duration was 60 minutes consisting of two coding questions, every 30 points. I partially solved 2nd one, the solution didn’t suffice for test cases with large inputs.

**A Special String: **You are given a string S consisting of lowercase Latin alphabets a-z. Find the minimum number of characters that must be changed to make S special. A string S is said to be special if and only if for all (S[i] , S[j] ) where (1 ≤ i ≤ N/2) and (N/2 + 1 ≤ j ≤ N) one of the following condition is true

- S[i] > S[j]
- S[i] < S[j]
- S[i] = S[j]

S[i] represents the ith character of string S (1 based Indexing ).

**Input Format:**

- The first line contains an integer T denoting the number of test cases.
- The first line of each test case contains an integer N denoting the length of S.
- The second line of each test case contains a string S.

**Output format: **Print an integer denoting the minimum number of changes required for each test case in a new line.

**Constraints **

1 ≤ T ≤ 5

1 ≤ N ≤ 10^{3 }

N is even

**Example :**

Input:1 6 aababcOutput:2

**Explanation:** Change S[4] = ‘d’ (1 based indexing) Change S[5] = ‘d’ New string = ‘aabddc’ Now all pair (S[i],S[j]) satisfy the second condition, S[i] < S[j]

**Generating Sequence: **You are given two strings A of length N and B of length M. These strings contain lowercase English alphabets. You are also given an integer K. You can change the character of *x* string A to any other characters *y*. The cost of this conversion is *abs*( ASCII(*x*)- ASCII(*y*) ). Find the minimum cost required such that the length of the longest common subsequence (LCS) of A and B is at least K.

**Note: **

- A subsequence of A string can be obtained by deleting zero or more characters in A.
- The longest common subsequence of two strings of A and B is a subsequence of A and B and has the maximum length among all strings that are a subsequence of A and B that would be multiple subsequences for two provided strings for example an LCS of vera and
*eats*is*ea*.

**Input Format:**

- The first line contains an integer T denoting the number of test cases for each test case.
- The first line of each test case contains three space-separated integers N, M, and K.
- The next line of each test case contains a string A.
- The next line of each test case contains a string B.

**Output format: **For each test case, print the minimum cost required in a new line.

**Constraints **

1 ≤ T ≤ 10

1 ≤ N, M ≤ 200

0 ≤ K ≤ *min*( N, M )

**Example:**

Input:2 5 4 3 abcba acyx 3 3 3 abc abcOutput:22 0