Minimal Changes to Form Palindrome

You are given a string s of length n. Your task is to determine the minimum number of changes required to transform s into a palindrome. A change consists of modifying a character at a given position. In a palindrome, for every index i (where \(0 \le i < \lfloor\frac{n}{2}\rfloor\)), the condition \(s[i] = s[n-i-1]\) must hold. Output the minimum number of such changes needed.

Constraints:

• 1 \(\le n \le 10^5\)
• s consists of lowercase English letters.

inputFormat

The input consists of a single line containing the string s.

outputFormat

Output a single integer denoting the minimum number of changes required to make the string a palindrome.

abca

1