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(input) {
    var reverse = input.split("").reverse().join("")
    var size = input.split("").length
    var count = 0
    for (var i=0; i< size/2; i++) {
      var a = input.split("")[i]
      var b = reverse.split("")[i]
      if (a !== b) {
        count = count + 1
      }
    }
    console.log(count)
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));