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 proconio::{input, fastout};
use proconio::marker::{Chars};
use std::cmp::*;

macro_rules! debug {
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
  }

#[fastout]
fn main() {
    input!{
        s: Chars,
    }

    let mut ok = true;
    if s[0]!='A' {
        ok = false;
    }
    if s[1]=='C' {
        ok = false;
    }
    if s[1].is_uppercase() {
        if s[1]!='A' {
            ok = false;
        }
    }
    let mut cnt = 0;
    for i in 2..s.len()-1 {
        if s[i]=='C' {
            if cnt==0 {
                cnt += 1;
            } else {
                ok = false;
                break;
            }
        } else {
            if s[i].is_uppercase() {
                if s[i]=='A' {
                    continue;
                } else {
                    ok = false;
                    break;
                }
            }
        }
    }

    if cnt==0 {
        ok = false;
    }

    if s[s.len()-1].is_uppercase() {
        if s[s.len()-1]!='A' {
            ok = false;
        }
    } 

    if ok==true {
        println!("AC");
    } else {
        println!("WA");
    }
}