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: Runtime Error)

package main

import (
	"fmt"
)

func main() {
	s := []string{}
	i := 0
	count := 0
	size := len(s)
	fmt.Scan(&s)
	for size == 0 {
		i++
		if s[i] == s[size] {
			s[size] = s[i]
			size--
			count++
		}
	}
}