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 Scala (2.11.7) (judge verdict: Accepted)

object Main extends App {
  val in = scala.io.Source.stdin.getLines.toSeq
  val S = in.head
  val f = S.take(2).toInt
  val s = S.drop(2).toInt
  private def month(n:Int):Boolean = {
    1 <= n && n <= 12
  }
  val mx = month(f)
  val xm = month(s) 
  
  if(mx && xm) println("AMBIGUOUS")
  else if(xm) println("YYMM")
  else if(mx) println("MMYY")
  else if(!(mx || xm)) println("NA")
  else println("XXXXXXXXX")
}