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 AtCoderA
{
    static void Main()
    {
        string s = Console.ReadLine();

        string front = s.Substring(0, 2);
        string end = s.Substring(2, 2);

        int f = int.Parse(front);
        int e = int.Parse(end);

        bool fValid = 0 < f && f <= 12;
        bool eValid = 0 < e && e <= 12;


        if (fValid && eValid)
        {
            Console.WriteLine("AMBIGUOUS");
        }
        else if (fValid)
        {
            Console.WriteLine("MMYY");
        }
        else if (eValid)
        {
            Console.WriteLine("YYMM");
        }
        else
        {
            Console.WriteLine("NA");
        }
    }
}