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: Wrong Answer)

<?php
$string = trim(fgets(STDIN));
$firstHalf = ltrim(substr($string, 0, 2), '0');
$secondHalf = ltrim(substr($string, 2), '0');

if (0 < $firstHalf && $firstHalf <= 12 && 0 < $secondHalf && $secondHalf <= 12) {
	echo 'AMBIGUOUS', PHP_EOL;
} elseif (0 < $firstHalf && $firstHalf <= 12 && 0 < $secondHalf && $secondHalf <= 99) {
    echo 'MMYY', PHP_EOL;
} elseif (0 < $firstHalf && $firstHalf <= 99 && 0 < $secondHalf && $secondHalf <= 12) {
	echo 'YYMM', PHP_EOL;
} else {
	echo 'NA', PHP_EOL;
}