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;

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).ok();
    let input = input.trim();
    let len = input.len();

    let mut input = input.chars();

    let mut i = 0;
    let mut countC = 0;
    let mut countU = 0;
    let mut ans = true;

    loop {
        i += 1;
        let buf = input.next();
        if let None = buf {
            break;
        }
        let buf = buf.unwrap();

        if i == 1 && buf != 'A' {
            ans = false;
            break;
        }
        if i >= 3 && i <= len - 1 {
            if buf == 'C' {
                countC += 1;
            }
        }
        if buf.is_uppercase() {
            countU += 1;
        }
    }
    if ans && countC == 1 && countU == 2 {
        println!("AC");
    } else {
        println!("WA");
    }
}