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 PHP (5.6.30) (judge verdict: Wrong Answer)

<?php
    fscanf(STDIN,'%s',$str);

    $a = (int)substr($str,0,2);
    $b = (int)substr($str,2,2);

    $c =false;
    $d = false;
    if($a > 0 && $a <= 12){
      $c = true;
    }
    if($b > 0 && $b <= 12){
      $d = true;
    }
    if($c){
      if($d){
        echo 'AMBIGUOUS';
      }else{
        echo 'MMYY';
      }
    }else{
      if($d){
        echo 'YYMM';
      }else{
        echo 'NN';
      }
    }
?>