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 Debug.Trace
import Data.Char

check0 :: String -> Bool
check0 [] = False
check0 (h:_) = h == 'A' 

check1 :: String -> Bool
check1 s = 
    let (_, mm) = splitAt 2 s in
    let (m, _) = splitAt (length mm - 1)  mm in
    let num = length $ filter ('C' ==) m in
    num == 1

check2 :: String -> Bool
check2 s = 
    let (ll, mm) = splitAt 2 s in
    let (m, r) = splitAt (length mm - 1)  mm in
    let (_, l) = splitAt 1 ll in
    and (map isLower l) && and (map isLower r) && and (map (\x -> isLower x || x == 'C') m)

solve :: String -> String
solve s
    |  check0 s && check1 s && check2 s  = "AC"
    | otherwise = "WA"

main :: IO ()
main = do
    s <- getLine
    putStrLn $ solve s