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 JavaScript (node.js v5.12) (judge verdict: Accepted)

'use strict';

function main(stdin) {
  const input = stdin;
  const former = parseInt(input.slice(0, 2), 10);
  const latter = parseInt(input.slice(2), 10);

  function test(n) {
    if (n < 1 || n > 12) return false;
    else return true;
  }

  const f = test(former);
  const l = test(latter);

  if (f) {
    if (l) console.log('AMBIGUOUS');
    else console.log('MMYY');
  } else {
    if (l) console.log('YYMM');
    else console.log('NA');
  }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));