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: Accepted)

def resolve():
    import sys
    import os
    input = sys.stdin.readline
    
    S = input().rstrip(os.linesep)
    pre = S[:2]
    suf = S[2:]

    def can_MM(string):
        if int(string) <= 12 and int(string) >= 1: # MM or YY
            return True
        else:
            return False

    pre_mm = can_MM(pre)
    suf_mm = can_MM(suf)

    if pre_mm:
        if suf_mm:
            print("AMBIGUOUS")
        else:
            print("MMYY")
    else:
        if suf_mm:
            print("YYMM")
        else:
            print("NA")
    

if __name__ == "__main__":
    resolve()