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 Python (3.4.3) (judge verdict: Wrong Answer)

def is_month(input_str):
  if 1 <= int(input_str) and int(input_str) <= 12:
    return True
  else:
    return False
    
def is_year(input_str):
  if 0 <= int(input_str) and int(input_str) <= 99:
    return True
  else:
    return False

s=input().strip()
first_half = [is_month(s[:2]), is_year(s[:2])]
second_half = [is_month(s[2:]), is_year(s[2:])]

if (first_half == [True, True] and second_half == [True, True]):
  print('AMBIGUOUS')
elif first_half[0] is True and second_half[1] is True:
  print('MMYY')
elif first_half[1] == False and second_half[0] is True:
  print('YYMM')
else:
  print('NA')