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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;
public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    String str = scan.next();
    StringBuilder sb = new StringBuilder(str);
    StringBuilder re = sb.reverse();
    int count = 0;
    int length = sb.length();
    if (length % 2 == 1) {
      length++;
    }
    for (int i = 0;i < sb.length()/2;i++) {
      if (sb.charAt(i) != re.charAt(i)) {
        count++;
      }
    }
      
    System.out.println(count);
  }
}