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: Wrong Answer)

month = ["01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12"]
a = gets.chomp.chars.map(&:to_s)

front = a[0] + a[1]
back = a[2] + a[3]

flg = 0
format = ""
if front != "00" && month.include?(back)
  flg += 1
  format = "YYMM"
end

if back != "00" && month.include?(front)
  flg += 1
  format = "MMYY"
end

if flg == 2
  puts "AMBIGUOUS"
elsif flg == 1
  puts format
else
  puts "NA"
end