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"
    "strings"
)

func main() {
	var S string
	var s []string
	var r []string
	var N int

	N = 0
	r = []string{}

	fmt.Scan(&S)
	s = strings.Split(S, "")

	for i := 0; i < len(s); i++ {
		r = append(r, s[len(s)-i-1])
	}

	for i := 0; i < len(s)/2; i++ {
		if s[i] != r[i] {
			N++
		}
	}
    fmt.Println(N)
}