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.*;
import java.util.*;
import java.math.*;
 
public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      	String s = sc.next();
      
      	int res = 0;
        	
      	char[] c = s.toCharArray();
      	int left = 0;
      	int right = c.length-1;
      	while ( left < right ){
        	if ( c[left] != c[right] ){
            	res++;
            }
         	left++;
          	right--;
        }
      	System.out.println( res );
      	
    }
}