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 5.4.1) (judge verdict: Time Limit Exceeded)

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

int main(){
  char s[256];
  int count =0;
  scanf("%s",s);


  char transfered[256];
  
 do{
    int k=0;
    for(int i=strlen(s)-1;i>=0;i--){
      transfered[k]=s[i];
      k++;
    }       
    for(int i= 0;i<strlen(s);i++){
      if(s[i]!=transfered[i]){
	s[i]=transfered[i];
	count++;
	break;
      }
    }}while(strcmp(s,transfered));
  
  printf("%d\n",count);
  return 0;
  
}