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 Java7 (OpenJDK 1.7.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.lang.String;

public class Main {

    public static void main(String[] args) {
        int A1;
        int num = 0;
        Scanner scan = new Scanner(System.in);
        String S = scan.nextLine();
        A1 = S.length();
        for(int i=0; i<(A1/2); i++){
            if(S.charAt(i) != S.charAt(A1-i-1)){
                num++;
            }
        }
        System.out.println(num);
    }
}