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 (Clang 3.8.0) (judge verdict: Accepted)

#include<stdio.h>
#include<string.h>

int main(){
  char s[100];
  int hug=0,i,j,x;

  scanf("%s",s);
  x=strlen(s);
  
    if(x%2==1){
    for(i=0;i<(x-1)/2;i++){
      if(s[i]!=s[x-i-1]){
	hug++;
      }
    }
  }	
  else{
    for(j=0;j<x/2;j++){
      if(s[j]!=s[x-j-1]){
	hug++;
     }
    }
  }

  printf("%d",hug);
}