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

solve1 :: String -> Bool
solve1 (s : sx)
  | s == 'A' = (solve2 sx)
  | otherwise = False

solve2 :: String -> Bool
solve2 (s : sx)
  | s == (toLower s) = solve3 sx False
  | otherwise = False

solve3 :: String -> Bool -> Bool
solve3 [] b
  | b = True
  | otherwise = False
solve3 (s : sx) b
  | s == 'C' && (b == True || (length sx) < 1) = False
  | s == 'C' = solve3 sx True
  | s /= (toLower s) = False
  | otherwise = solve3 sx b

main = do
  s <- getLine
  if (solve1 s)
  then putStrLn "AC"
  else putStrLn "WA"