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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

module Main where

import           Data.Char                    (isLower)
import           Text.ParserCombinators.ReadP (ReadP, char, eof, many1,
                                               readP_to_S, satisfy)

main :: IO ()
-- interact を使うと一部失敗する
-- main = interact $ show . f
main = print . f =<< getLine

f :: String -> Result
f s = if not . null . readP_to_S parser $ s then AC else WA

parser :: ReadP ()
parser = char 'A' *> many1 lowerChar *> char 'C' *> many1 lowerChar *> eof

lowerChar :: ReadP Char
lowerChar = satisfy isLower

data Result
  = AC
  | WA
  deriving (Show, Eq)

tests :: [Bool]
tests =
  [ test1
  , test2
  , test3
  , test4
  , test5
  ]

test1, test2, test3, test4, test5 :: Bool
test1 = f "AtCoder" == AC
test2 = f "ACoder" == WA
test3 = f "AcycliC" == WA
test4 = f "AtCoCo" == WA
test5 = f "Atcoder" == WA