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)

# N, K = gets.chomp.split.map(&:to_i)
S = gets.chomp

#Ex. YYMM
# YY is 00-99, MM is 01-12
# So, we check "pre" and "sub"

# 01-12, month or year
# 00, 13-99, year

# pattern
# OK: year-(month or year)
# OK: (month or year)-year
# AMBIGUOUS: (month or year)-(month or year)
# NA: year-year

pre = S[0..1]
sub = S[2..-1]

def month_or_year?(s)
  i = s.to_i
  return (1 <= i && i <= 12)
end

p = month_or_year?(pre)
s = month_or_year?(sub)

if p && s 
  print "AMBIGUOUS\n"
elsif p && !s
  print "MMYY\n"
elsif !p && s
  print "YYMM\n"
else # !p && !s
  print "NA\n"
end