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 Ruby (2.3.3) (judge verdict: Accepted)

#
# File    : B.rb
# Author  : Kazune Takahashi
# Created : 5/19/2019, 9:03:56 PM
# Powered by Visual Studio Code
#

s = gets.chomp

a = s[0...2].to_i
b = s[2...4].to_i

ax = (1 <= a && a <= 12)
bx = (1 <= b && b <= 12)

if ax && bx
  puts "AMBIGUOUS"
elsif ax
  puts "MMYY"
elsif bx
  puts "YYMM"
else
  puts "NA"
end