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;
using System.Collections.Generic;
using System.Linq;
using System.Text;


public class A
{
  
    public static void Main(string[] args)
    {
        int t = 1;
        while (t > 0)
        {
            //var arr = Console.ReadLine().Trim().Split().Select(x => int.Parse(x)).ToArray();
            var s = Console.ReadLine().Trim();
            var totalHugs = 0;
            for(int i = 0; i < s.Length / 2; i++)
            {
                if(s[i] != s[s.Length - i - 1])
                {
                    totalHugs++;
                }
            }
            Console.WriteLine(totalHugs);
            t--;
        }
    }
}