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;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        string s = Console.ReadLine();
        int front = int.Parse(s[0].ToString()) * 10 + int.Parse(s[1].ToString());
        int back = int.Parse(s[2].ToString()) * 10 + int.Parse(s[3].ToString());
        bool isYYMM = false;
        bool isMMYY = false;
        Console.WriteLine(front);
        Console.WriteLine(back);
        if (front != 0 && back >= 1 && back <= 12)
            isYYMM = true;
        if (back != 0 && front >= 1 && front <= 12)
            isMMYY = true;

        string ans = "";
        if (isYYMM && isMMYY)
            ans += "AMBIGUOUS";
        else if (!isYYMM && !isMMYY)
            ans += "NA";
        else if (isYYMM && !isMMYY)
            ans += "YYMM";
        else if(isMMYY && !isYYMM)
            ans += "MMYY";

        Console.WriteLine(ans);

    }
}