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: Wrong Answer)

use std::io;

fn read_input() -> String {
    let mut s = String::new();
    io::stdin().read_line(&mut s);
    s
}

fn wa() {
    println!("WA");
    std::process::exit(0);
}

fn solve(s: String) {
    if !s.starts_with('A') {
        wa();
    }

    let v: Vec<_> = s.chars().collect();

    let mut count = 0;
    for c in &v[2..s.len()-1] {
        if *c == 'C' {
            count += 1;
        }
    }
    if count != 1 {
        wa();
    }

    count = 0;
    for c in &v {
        match *c {
            'A'...'Z' => count += 1,
            _ => ()
        }
    }

    if count != 2 {
        wa();
    }

    println!("AC");
}

fn main() {
    solve(read_input());
}