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;

public class Program{
    public static void Main(){
        string s = Console.ReadLine();
        string[] numbers = new string[2];
        numbers[0] = s.Substring(0,2);
        numbers[1] = s.Substring(2);
        bool[] monthFlag = new bool[2];
        for(var i = 0; i < 2; i++){
            var num = 0;
            if(numbers[i][0] == '0'){
                num = int.Parse(numbers[i].Substring(1));
            }else{
                num = int.Parse(numbers[i]);
            }
            
            if(num > 0 && num < 13){
                monthFlag[i] = true;
            }
        }
        if(monthFlag[0] && monthFlag[1]){
            Console.WriteLine("AMBIGUOUS");
        }else if(!monthFlag[0] && monthFlag[1]){
            Console.WriteLine("YYMM");
        }else if(monthFlag[0] && !monthFlag[1]){
            Console.WriteLine("MMYY");
        }else{
            Console.WriteLine("NA");
        }
    }
}