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 Kotlin (1.0.0) (judge verdict: Accepted)

import java.util.Scanner

fun a(sc: Scanner): String {
    if (sc.nextInt() + sc.nextInt() + sc.nextInt() < 22) {
        return "win"
    }
    return "bust"
}

fun b(sc: Scanner): String {
    val s = sc.next()
    val sr = s.reversed()
    val l = s.length
    var ans = 0
    s.forEachIndexed { index, c ->
        if (index * 2 >= l) {
            return ans.toString()
        }
        if (c != sr[index]) ans++
    }
    return "0"
}

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    println(
//        a(sc)
        b(sc)
    )
}