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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

public class ABC0126_A2 {
    private static void Main(string[] args) {
        var input = Console.ReadLine().Trim();
        Prepare(input);
    }

    private static void Prepare(string input) {
        var numbers = new int[] {
            int.Parse(input) / 100,
            int.Parse(input) % 100,
        };

        Compute(numbers);
    }

    private static void Compute(int[] numbers) {
        if (IsYYMM(numbers) && IsMMYY(numbers))
            OutputAnswer("AMBIGUOUS");

        else if (IsYYMM(numbers))
            OutputAnswer("YYMM");

        else if (IsMMYY(numbers))
            OutputAnswer("MMYY");

        else
            OutputAnswer("NA");
    }

    private static void OutputAnswer(string text) => Console.WriteLine(text);
    private static bool IsYYMM(int[] numbers) => (1 <= numbers[1]) && (numbers[1] <= 12);
    private static bool IsMMYY(int[] numbers) => (1 <= numbers[0]) && (numbers[0] <= 12);
}