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_day(n):
    return n <= 31 and n >= 1

def is_month(n):
    return n <= 12 and n >= 1

s = input()

f, e = s[:2], s[2:]

e_is_month = False
f_is_month = False

if is_month(int(f)):
    f_is_month = True

if is_month(int(e)):
    e_is_month = True

if not f_is_month and e_is_month:
    if is_day(int(f)):
        print("YYMM")
    else:
        print("NA")
elif f_is_month and not e_is_month:
    if is_day(int(e)):
        print("MMYY")
    else:
        print("NA")
else:
    if e_is_month and f_is_month:
        print("AMBIGUOUS")
    else:
        print("NA")