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 Scala (2.13.1) (judge verdict: Accepted)

import scala.math.abs

object Main extends App {
  
  val sc = new java.util.Scanner(System.in)
  val s = sc.next().toList
  val part = s.slice(2, s.length - 1)
  val cIndex = part.indexOf('C') + 2
  val map = part.groupMapReduce(identity)(_ => 1)(_ + _)
  if (s.head == 'A' && map.getOrElse('C', 0) == 1 && isLower(s)) {
    println("AC")
  } else {
    println("WA")
  }
  
  def isLower(s: List[Char]): Boolean = {
    (0 until s.length).forall{ i =>
      if (i != 0 && i != cIndex) {
        s(i).isLower
      } else {
        true
      }
    }  
  }
}