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: Wrong Answer)

package main
 
import (
  "fmt"
  "os"
  "bufio"
)
 
func main() {
 reader := bufio.NewReader(os.Stdin)
  str, _ := reader.ReadString('\n')
  length := len(str)
  mid := length / 2
  hugs := 0
  for i := 0; i < mid; i++ {
    if str[i] != str[length-1-i] {
      hugs++
    }
  }
  fmt.Println(hugs)
}