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: Accepted)

#include <stdio.h>
int main(void)
{
    char *str1;
    str1 = (char *)malloc(sizeof(char) * 100);
    scanf("%s", str1);
    int center = 0;
    int L = strlen(str1);
    int count = 0;
    if(L%2==0){
        for(int i=0;i<L/2;i++){
            if(str1[i]!=str1[L-i-1]){
                count++;
            }
        }
    }else{
        int center = (L-1)/2;
        for(int i=0;i<center;i++){
            if(str1[i]!=str1[L-i-1]){
                count++;
            }
        }
    }
    printf("%d",count);
    return 0;
}