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)

inputs = Array.new
while line = $stdin.gets
  inputs << line.chomp
end

S = inputs[0]
ff = S[0..1].to_s.to_i
ll = S[2..3].to_s.to_i

is_yymm = false
is_mmyy = false

# check ll
if ll > 0 && ll <= 12 && ff > 0 && ff <= 12
  is_yymm = true
  is_mmyy = true
elsif (ff > 0 && ff <= 12) && (ll > 12 || ll == 0)
  is_yymm = false
  is_mmyy = true
elsif (ff > 12 || ff == 0) && (ll > 0 && ll <= 12)
  is_yymm = true
  is_mmyy = false
else
  is_yymm = false
  is_mmyy = false
end

if is_yymm && is_mmyy
  puts "AMBIGUOUS"
elsif !is_yymm && !is_mmyy
  puts "NA"
elsif is_yymm && !is_mmyy
  puts "YYMM"
elsif !is_yymm && is_mmyy
  puts "MMYY"
end