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 System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp15 {
    class Program {
        static void Main(string[] args) {
            //入力
            string S = Console.ReadLine();

            //前半二文字
            string before = S.Substring(0, 2);
            //後半二文字
            string after = S.Substring(2, 2);

            //月の可能性をまとめたリスト
            string[] month = {"01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12" };

            //回答となる文字列
            string ans;

            //実行
            if (month.Contains(before) && month.Contains(after)) {
                ans = "AMBIGUOUS";
            } else if (month.Contains(before)) {
                ans = "MMYY";
            } else if (month.Contains(after)) {
                ans = "YYMM";
            } else {
                ans = "NA";
            }

            //出力
            Console.WriteLine(ans);
        }
    }
}