Problem:
Score : 200 points

Problem Statement

You are given a string S. Each character of S is uppercase or lowercase English letter.
Determine if S satisfies all of the following conditions:

The initial character of S is an uppercase A.

There is exactly one occurrence of C between the third character from the beginning and the second to last character (inclusive).

All letters except the A and C mentioned above are lowercase.

Constraints

4 ≤ |S| ≤ 10 (|S| is the length of the string S.)

Each character of S is uppercase or lowercase English letter.

Input

Input is given from Standard Input in the following format:

S

Output

If S satisfies all of the conditions in the problem statement, print AC; otherwise, print WA.

Sample Input 1

AtCoder

Sample Output 1

AC

The first letter is A, the third letter is C and the remaining letters are all lowercase, so all the conditions are satisfied.

Sample Input 2

ACoder

Sample Output 2

WA

The second letter should not be C.

Sample Input 3

AcycliC

Sample Output 3

WA

The last letter should not be C, either.

Sample Input 4

AtCoCo

Sample Output 4

WA

There should not be two or more occurrences of C.

Sample Input 5

Atcoder

Sample Output 5

WA

The number of C should not be zero, either.

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io::stdin;

fn is_ascii_uppercase(a: char) -> bool {
    match a as u8 {
        x if 65 <= x && x <= 90 => true,
        _ => false,
    }
}

fn main() {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let s = s.trim();
    let l = s.chars().count();

    let f1 = || if let Some(0) = s.find('A') { true } else { false };
    let f2 = || s.chars().take(l - 1).skip(2).filter(|&a| a == 'C').count() == 1;
    let f3 = || s.chars().skip(1).filter(|&a| is_ascii_uppercase(a) && (a != 'C')).count() == 0;

    println!("{}", if f1() && f2() && f3() { "AC" } else { "WA" });
}