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;
using static System.Console;
using static System.Math;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TemplateAlgorithm
{
    class Program
    {
        public const long Inf = (long)1e18;
        public const double eps = 1e-6;
        public const string alfa = "abcdefghijklmnopqrstuvwxyz";
        public const string ALFA = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        public const int MOD = 1000000007;


        static void Main(string[] args)
        {
            string s = IO.ReadStr();

            int yy, mm;
            yy = int.Parse(s.Substring(0, 2));
            mm = int.Parse(s.Substring(2, 2));

            if ((1 <= yy && yy <= 12) && (1 <= mm && mm <= 12))
            {
                IO.Cout("AMBIGUOUS");
            }
            else if ((1 <= mm && mm <= 12))
            {
                IO.Cout("YYMM");
            }
            else if ((1 <= yy && yy <= 12))
            {
                IO.Cout("MMYY");
            }
            else IO.Cout("NA");
        }

        static int ToInt(char c) => c - '0';



        #region MIN,MAX

        /// <summary>
        /// 最大値を返す
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="vals"></param>
        /// <returns></returns>
        public static T MaxValue<T>(params T[] vals) => vals.Max();

        /// <summary>
        /// 最小値を返す
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="vals"></param>
        /// <returns></returns>
        public static T MinValue<T>(params T[] vals) => vals.Min();
        #endregion
    }

    #region IO

    /// <summary>
    /// IO
    /// </summary>
    public class IO
    {
        public static string ReadStr(bool isTrim = false) => (isTrim) ? ReadLine().Trim() : ReadLine();
        public static int ReadInt() => int.Parse(ReadStr());

        public static long ReadLong() => long.Parse(ReadStr());

        public static decimal ReadDecimal() => decimal.Parse(ReadStr());
        public static double ReadDouble() => double.Parse(ReadStr());
        public static string[] ReadStrArr(char separator = ' ') => ReadLine().Split(separator);
        public static int[] ReadIntArr() => Array.ConvertAll(ReadStrArr(), int.Parse);
        public static long[] ReadLongArr() => Array.ConvertAll(ReadStrArr(), long.Parse);

        public static decimal[] ReadDecimalArr() => Array.ConvertAll(ReadStrArr(), decimal.Parse);
        public static double[] ReadDoubleArr() => Array.ConvertAll(ReadStrArr(), double.Parse);

        public static void Cout<T>(T value) => WriteLine(value);
        public static void CoutJoin<T>(T[] values, string separator = " ") => Cout(string.Join(separator, values));
    }

    #endregion    
}