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;

namespace Contest148
{
	class Program
	{
		static void Main(string[] args)
		{
			string strs = Console.ReadLine();
			char str1;
			char str2;
			int count = strs.Length / 2;
			int numOfHug = 0;
			for(int i = 0; i < count; i++)
			{
				str1 = strs[i];
				str2 = strs[strs.Length - (i + 1)];

				if(str1 == str2)
				{
					continue;
				}
				else
				{
					numOfHug++;
				}
			}

			Console.WriteLine(numOfHug);
		}
	}
}