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: Wrong Answer)

using System;

public class Program
{
    static void Main()
    {
        string S = Console.ReadLine();

        int a = int.Parse(S[0].ToString());
        int b = int.Parse(S[1].ToString());
        int c = int.Parse(S[2].ToString());
        int d = int.Parse(S[3].ToString());

        if(10 * a + b <= 12 && 10 * a + b != 0)
        {
            if(c * 10 + d <= 12 && 10 * a + b != 0)
            {
                Console.WriteLine("AMBIGUOUS");
            }
            else if(c * 10 + d > 12 || 10 * a + b == 0)
            {
                Console.WriteLine("MMYY");
            }
        }
        else if(10 * a + b > 12)
        {
            if(10 * c + d <= 12 && 10 * c + d != 0)
            {
                Console.WriteLine("YYMM");
            }
            else if(10 * c + d > 12 || 10 * c + d == 0)
            {
                Console.WriteLine("NA");
            }
        }
    }
}