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: Accepted)

import java.io.IOException;
import java.util.Scanner;

class Main {
    private static final Scanner scanner = new Scanner(System.in);
    public static void main(final String[] args) throws IOException {
            String s = scanner.nextLine();
            int ans = 0;
            for (int i = 0; i < (s.length()/2); i++) {
                if (!s.substring(i, i + 1).equals(s.substring(s.length()-i -1, s.length()-i))) {
                    ans++;
                }
            }
            System.out.println(ans);
        }
}