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 (2.11.7) (judge verdict: Accepted)

object Main extends App {

val s_list = scala.io.StdIn.readLine.toList

def check(s_list:List[Char]):Boolean = {
  if (s_list(0) != 'A') return false
  val upper_c_idx = s_list.indexOfSlice("C")
  if (upper_c_idx != s_list.lastIndexOfSlice("C")) return false
  if ((upper_c_idx < 2) | (s_list.length-2 < upper_c_idx)) return false
  var cnt:Int = s_list.filter(c => c >= 'A' && c <= 'Z').size
  if (cnt > 2) return false
  return true
}

if (check(s_list)) println("AC") else println("WA")
}