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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
)

func reverse(s string) string {
	ans := ""
	for i, _ := range s {
		ans += string(s[len(s)-i-1])
	}
	return string(ans)
}

func main() {
	var w string
	fmt.Scan(&w)

	length := len(w)
	var half int
	if length%2 == 0 {
		half = length / 2
	} else {
		half = (length / 2) + 1
	}
	h1 := w[:(length / 2)]
	h2 := w[half:]
	rh2 := reverse(h2)
	var count int
	for i := 0; i < len(h1); i++ {
		if h1[i] != rh2[i] {
			count++
		}
	}
	fmt.Println(count)
}