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 (1.42.0) (judge verdict: Accepted)

use whiteread::parse_line;

fn main() {
    let s: String = parse_line().unwrap();
    let mut iter = s.as_str().chars();
    let mut flag = false;

    if iter.next() != Some('A') {
        println!("WA");
        return;
    }
    if !iter.next().unwrap().is_lowercase() {
        println!("WA");
        return;
    }
    for _ in 0..s.len() - 3 {
        let c = iter.next();
        if c == Some('C') {
            flag = true;
            break;
        } else if !c.unwrap().is_lowercase() {
            println!("WA");
            return;
        }
    }
    for c in iter {
        if !c.is_lowercase() {
            println!("WA");
            return;
        }
    }
    if flag {
        println!("AC");
    } else {
        println!("WA");
    }
}