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: Wrong Answer)

#include<stdio.h>
#define N 100
 
int main(){
 
	int m;
	int Ans=0;
 
	char S[N];
	scanf("%s",S);
	for(m=0; S[m]!='\0'; ++m);
 
 int i = 0;
  while(S[i] < S[m - 1 - i]){
  	if(S[i] != S[m - 1 - i]){
		S[m - i] = S[i];
		Ans++;
  	}	
 	i++;
 }
  	printf("%d",Ans);
	return 0;
}