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: Runtime Error)

#include <stdio.h>

int main(void)
{
    char array1[50];
    int i, j, l;
    int count = 0;
    int hug = 0;
    scanf("%s", array1);

    for (i = 0; i < 50; i++)
    {
        if (array1[i] == '\0')
            break;
        count++;
    }

    j = count - 1;
    l = (count - 1) / 2;
    for (i = 0; i <= l; i++)
    {
        if (array1[i] == array1[j - i])
        {
        }
        else
        {
            hug++;
        }
    }

    printf("%d\n", hug);

    return 0;
}