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;
 
class Program {
  static void Main (string[] args) {
    string s = Console.ReadLine();
    string s1 = s.Substring(0, 2);
    string s2 = s.Substring(2);
    int i1 = (s1[0] != '0') ? int.Parse(s1) : int.Parse(s1[1].ToString());
    int i2 = (s2[0] != '0') ? int.Parse(s2) : int.Parse(s2[1].ToString());
    bool a = false;
    bool b = false;
    if (i1 >= 1 && i1 <= 12) {
      a = true;
    }
    if (i2 >= 1 && i2 <= 12) {
      b = true;
    }
    if (!a && !b) {
      Console.WriteLine("NA");
    } else if (a && b) {
      Console.WriteLine("AMBIGUOUS");
    } else if (a && !b) {
      Console.WriteLine("MMYY");
    } else if (!a && b) {
      Console.WriteLine("YYMM");
    }
  }
}