Problem:
Score : 200 points

Problem Statement

Takahashi loves palindromes. Non-palindromic strings are unacceptable to him. Each time he hugs a string, he can change one of its characters to any character of his choice.

Given is a string S. Find the minimum number of hugs needed to make S palindromic.

Constraints

S is a string consisting of lowercase English letters.

The length of S is between 1 and 100 (inclusive).

Input

Input is given from Standard Input in the following format:

S

Output

Print the minimum number of hugs needed to make S palindromic.

Sample Input 1

redcoder

Sample Output 1

1

For example, we can change the fourth character to o and get a palindrome redooder.

Sample Input 2

vvvvvv

Sample Output 2

0

We might need no hugs at all.

Sample Input 3

abcdabc

Sample Output 3

2

Solution in Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.*;
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    int leg = s.length();
    String s_l = s.substring(0,leg/2);
    String s_r = s.substring(leg/2);

    int c_l = 0;
    int c_r = leg/2-1;
    
    int count = 0;
    
    for(int i = 0 ; i < leg/2 ; ++i){
      if(s_l.charAt(c_l) != s_r.charAt(c_r)){
        count++;
      }
      c_l++;
      c_r--;
    }
    
    if(leg%2==0 ||count==0){
      System.out.println(count);
    }else{
      System.out.println(count-1);
    }
  }
}