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: Accepted)

import java.util.*;
class Main{
	public static void main(String args[]){
    	Scanner sc = new Scanner(System.in);
      	String s = sc.nextLine();
      	int count = 0;
      	int i = 0, j = s.length() - 1;
      	while( i < j){
          if(s.charAt(i) != s.charAt(j))
            count++;
          i++;
          j--;
        }
      System.out.println(count);
    }
}