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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php

//標準入力
class Scanner {
  private $arr = [];
  private $count = 0;
  private $pointer = 0;
  public function next() {
      if($this->pointer >= $this->count) {
          $str = trim(fgets(STDIN));
          $this->arr = explode(' ', $str);
          $this->count = count($this->arr);
          $this->pointer = 0;
      }
      $result = $this->arr[$this->pointer];
      $this->pointer++;
      return $result;
  }
  public function hasNext() {
      return $this->pointer < $this->count;
  }
  public function nextInt() {
      return (int)$this->next();
  }
  public function nextDouble() {
      return (double)$this->next();
  }
}

//標準出力
class out {
    public static function println($str = "") {
        echo $str . PHP_EOL;
    }
}

/* 標準入力からの受取
$sc = new Scanner();

#数値(スペース区切り対応)
$n = $sc->nextInt();

#文字(スペース区切り対応)
$str = $sc->next();

#改行込みの文字列を配列に格納
$str=[];
$str[] = $sc->next();
$str[] = $sc->next();
var_dump($str);

*/



$sc = new Scanner();
$s = $sc->next();


$a = substr($s, 0, 2);
$b = substr($s, 2, 2);
$ans = "";


if($a === "00" || $b === "00"){
  $ans = "NA";
}

if ((int)$a > 0 and (int)$a <= 12){
  $a_MM = 1;
}elseif ((int)$a > 0 and (int)$a <= 99){
  $a_MM = 0;
}
if ((int)$b > 0 and (int)$b <= 12){
  $b_MM = 1;
}elseif ((int)$b > 0 and (int)$b <= 99){
  $b_MM = 0;
}

if($a_MM and $b_MM){
  $ans = "AMBIGUOUS";
}elseif($a_MM){
  $ans = "MMYY";
}elseif($b_MM){
  $ans = "YYMM";
}else{
  $ans = "NA";
}


echo $ans.PHP_EOL;

?>