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# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

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

class main{
  public static void Main(string[] args){
    string s = Console.ReadLine();
    char[] former = new char[s.Length/2];
    char[] latter = new char[s.Length/2];
    int cnt = 0;
    
    for(int i = 0; i < former.Length; i++){
      former[i] = s[i];
      latter[i] = s[s.Length - 1 - i];
      Console.WriteLine(former[i]);
      Console.WriteLine(latter[i]);
      
      if(former[i] != latter[i]) cnt++;
    }
    Console.WriteLine(cnt);
  }
}