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;
use std::str::FromStr;

fn input<T:FromStr>() -> T {
  let mut line: String = String::new();
  io::stdin().read_line(&mut line);
  line.trim().parse().ok().unwrap()
}

fn main() {
  let s: String = input();
  let s_vec:Vec<char> = s.chars().collect();
  //println!("{:?}", s_vec);
  let len = s_vec.len();
  if s_vec[0] != 'A' || s_vec[len-1].is_uppercase() || s_vec[1].is_uppercase() {
    println!("WA");
    return;
  }
  let mut count = 0;
  let mut i = 0;

  for c in s_vec {
    if i > 1 && i != len{
      if c.is_uppercase() {
        if c == 'C' {
          count += 1;
        } else {
          println!("WA");
          return;
        }
        if i == len - 1 {
          println!("WA");
          return;
        }
      }
    }
    i += 1;
  }
  if count != 1 {
    println!("WA");
  } else {
    println!("AC");
  }

}