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)

'use strict';
function main(input) {
  const arr = input.trim().split('\n');
  const a = arr[0];
  const length = a.length;
  let count = 0;

  for (let i = 0; i < Math.ceil(length / 2); i ++) {
    if (a[i] === a[length - 1 - i]) {
      count++;
    }
  }
  
  console.log(count);
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));