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# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Linq;

namespace abc126A
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = int.Parse(Console.ReadLine());
            int a2 = a % 100;
            int a1 = (a - a2)/100;
            bool ym = false;
            bool my = false;
            if (a1 == 01 && a2 <= 31) ym = true;
            if (a1 == 02 && a2 <= 28) ym = true;
            if (a1 == 03 && a2 <= 31) ym = true;
            if (a1 == 04 && a2 <= 30) ym = true;
            if (a1 == 05 && a2 <= 31) ym = true;
            if (a1 == 06 && a2 <= 30) ym = true;
            if (a1 == 07 && a2 <= 31) ym = true;
            if (a1 == 08 && a2 <= 31) ym = true;
            if (a1 == 09 && a2 <= 30) ym = true;
            if (a1 == 10 && a2 <= 31) ym = true;
            if (a1 == 11 && a2 <= 30) ym = true;
            if (a1 == 12 && a2 <= 31) ym = true;
            if (a2 == 01 && a1 <= 31) my = true;
            if (a2 == 02 && a1 <= 29) my = true;
            if (a2 == 03 && a1 <= 31) my = true;
            if (a2 == 04 && a1 <= 30) my = true;
            if (a2 == 05 && a1 <= 31) my = true;
            if (a2 == 06 && a1 <= 30) my = true;
            if (a2 == 07 && a1 <= 31) my = true;
            if (a2 == 08 && a1 <= 31) my = true;
            if (a2 == 09 && a1 <= 30) my = true;
            if (a2 == 10 && a1 <= 31) my = true;
            if (a2 == 11 && a1 <= 30) my = true;
            if (a2 == 12 && a1 <= 31) my = true;
            if (ym == true && my == true) Console.WriteLine("AMBIGUOUS");
            if (ym == true && my == false) Console.WriteLine("MMYY");
            if (ym == false && my == true) Console.WriteLine("YYMM");
            if (ym == false && my == false) Console.WriteLine("NA");
        }

    }
}