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 Rust (1.15.1) (judge verdict: Accepted)

fn main() {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();

    let target_line = line.trim();

    let word_length = target_line.len();
    let run = word_length / 2;

    let mut hug_count = 0;
    for i in 0..run {
        let head_c = target_line.as_bytes().get(i).unwrap();
        let tail_c = target_line.as_bytes().get(word_length - i - 1).unwrap();
        if head_c != tail_c {
            hug_count += 1;
        }
    }

    println!("{}", hug_count);
}