Write simple python/java program and also explain the logic because i am crying so much and not able to understand anything.

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 10³

N is even

Example :

Input: 1 6 aababc Output: 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 abc Output: 22 0