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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function main(arg) {
    var n = arg.length;
    var ijougen = Math.floor(n/2);
    var kekka = 0;
    for(i=0;i<ijougen;i++){
    	if(arg.charAt(i)!=arg.charAt(n-i-1)){
    		kekka += 1;
    	}
    }
    console.log(kekka.toString());
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));