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)

import           Data.Char

main :: IO ()
main = do
    s <- getLine :: IO String
    putStrLn $ if judge s then "AC" else "WA"

judge :: String -> Bool
judge s = ahead s && celem s && small s

ahead :: String -> Bool
ahead s = head s == 'A'

celem :: String -> Bool
celem s =
    let n  = length s
        si = drop 2 (take (n - 1) s)
    in  'C' `elem` si

small :: String -> Bool
small s = length (filter isUpper s) == 2