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 (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
int main()
{
   char S[100];
   scanf("%s",S);
   int l,i,a,b=0;
   l=strlen(S);
  if(l%2==0)
  {
    for(i=0;i<l/2;i++)
    {
      if(S[i]==S[l-i-1])
      a=0;
      else
       b++;
    }
    printf("%d",b);
  }
  else 
  {
    for(i=0;i<l-1/2;i++)
      {
      if(S[i]==S[l-i-1])
      a=0;
      else
       b++;
      }
    printf("%d",b);
  }
  return 0;
}