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.util.*;

public class Main{

	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		String S = sc.next();
		int Len = S.length();
		int count = 0;

			for(int i=0; i<Len/2; i++){
				char ch1 = S.charAt(i);
				char ch2 = S.charAt(Len -1 -i);
			
				if(ch1 != ch2){
					count++;
				}
			}
			System.out.println(count);

	}
}