Problem:
Score : 200 points

Problem Statement

You have a digit sequence S of length 4. You are wondering which of the following formats S is in:

YYMM format: the last two digits of the year and the two-digit representation of the month (example: 01 for January), concatenated in this order

MMYY format: the two-digit representation of the month and the last two digits of the year, concatenated in this order

If S is valid in only YYMM format, print YYMM; if S is valid in only MMYY format, print MMYY; if S is valid in both formats, print AMBIGUOUS; if S is valid in neither format, print NA.

Constraints

S is a digit sequence of length 4.

Input

Input is given from Standard Input in the following format:

S

Output

Print the specified string: YYMM, MMYY, AMBIGUOUS or NA.

Sample Input 1

1905

Sample Output 1

YYMM

May XX19 is a valid date, but 19 is not valid as a month. Thus, this string is only valid in YYMM format.

Sample Input 2

0112

Sample Output 2

AMBIGUOUS

Both December XX01 and January XX12 are valid dates. Thus, this string is valid in both formats.

Sample Input 3

1700

Sample Output 3

NA

Neither 0 nor 17 is valid as a month. Thus, this string is valid in neither format.

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

solve :: Int -> Int -> Int -> Int -> String
solve s1 s2 s3 s4 = case (b1, b2) of
  (True, True)   -> "AMBIGUOUS"
  (True, False)  -> "MMYY"
  (False, True)  -> "YYMM"
  (False, False) -> "NA"
  where isMonth d1 d2 = d1 * 10 + d2 `elem` [1..12]
        b1 = isMonth s1 s2
        b2 = isMonth s3 s4

main :: IO ()
main = do
  [s1, s2, s3, s4] <- map (read . (:[])) <$> getLine
  putStrLn $ solve s1 s2 s3 s4