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++14 (GCC 5.4.1) (judge verdict: Runtime Error)

#include<iostream>
#include<cstring>
using namespace std;

int lenght(char*str){ 
 int a=strlen(str);
 return a;
}

int main() {
    char str[10]; 
    cin >> str;
    int l = lenght(str);
 	int m = (l+1) / 2;
    int counter = 0;
    for (int i=0 ; i < m ; ++i) {
      	if (str[i] == str[l-i-1]) ++counter;
    }
 	int x = m - counter;
	cout << x << endl;
}