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 Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(defun betweenp (num inf sup)
  (if (>= num inf)
      (if (<= num sup)
          t
          nil)
      nil))

(defun convert-data (str)
  (list (parse-integer (subseq str 0 2)) (parse-integer (subseq str 2 4))))
(defun monthp (num)
  (betweenp num 1 12))

(defun yearp (num)
  (betweenp num 0 99))

(defun yymmp (lst)
  (and (yearp (car lst))
       (monthp (cadr lst))))

(defun mmyyp (lst)
  (and (monthp (car lst))
       (yearp (cadr lst))))

(defparameter input (read-line))
(let ((data (convert-data input)))
  (cond ((and (yymmp data)
              (mmyyp data)) (format t "AMBIGUOUS"))
        ((and (yymmp data)
              (not (mmyyp data))) (format t "YYMM"))
        ((and (not (yymmp data))
              (mmyyp data)) (format t "MMYY"))
        (t (format t "NA"))
        ))