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>
#include<string.h>
int main()
{
    int i,l,count=0,j;
    char s[101],s2[101];
    scanf("%s", s);
    l=strlen(s);
    for(i=l-1,j=0;i>=0;i--,j++)s2[j]=s[i];
    s2[j]='\0';
    printf("%s\n", s2);
    for(i=0;i<l;i++)
    {
        if(s[i]!=s2[i])count++;
    }
    printf("%d\n", count/2);
    return 0;
}