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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
public class test
{
  public static void Main(){
    var input = Console.ReadLine();
    
    var count = 0;
    if(input.Length % 2 == 0)
    {
      for(var i = 0 ; i < input.Length/2 ; i++)
      { 
        if(input[i] != input[input.Length-1-i])
        {
          count++;
        }
      }
    }
    else
    {
      for(var i = 0 ; i < (input.Length)/2+1 ; i++)
      { 
        if(input[i] != input[input.Length-1-i])
        {
          count++;
        }
      }
    }
    Console.WriteLine(count);
  }
}