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::BufReader;
use std::io::BufRead;
use std::io;

fn main() {
    let reader = io::stdin();
    let mut reader = BufReader::new(reader.lock());

    let mut s = String::new();

    let _ = reader.read_line(&mut s);
    let s = s.trim().to_string().as_bytes().to_vec();
    let len = s.len();

    if s[0] != 0x41 {
        println!("WA");
        std::process::exit(0);
    }

    let mut count = 0;
    let mut c_index = 0;

    for i in 2..(len - 1) {
        if s[i] == 0x43 {
            count += 1;
            c_index = i;
        }
    }

    if count == 1 {
        for i in 1..len {
            if s[i] < 0x61 && s[i] > 0x7a && i != c_index {
                println!("WC");
                std::process::exit(0);
            };
            if i == (len - 1) {
                println!("AC");
            }
        }
    }
    println!("WC");
}