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.Scanner;

public class Main{
	public static void main(String[] args){
		
		//long startTime = System.currentTimeMillis();
		
		Scanner sc=new Scanner(System.in);
		String moji=sc.next();
		char[] c=moji.toCharArray();
		int size=moji.length();
		
		int orikaeshi;
		if(size%2==0)orikaeshi=size/2-1;
		else orikaeshi=(size-1)/2-1;
		
		int count=0;
		
		for(int i=0;i<=orikaeshi;i++){
			if(c[i]!=c[size-1-i]){
				count++;
				//System.out.println(c[i]);
			}
		}
		
			System.out.println(count);
		
		
	}
}