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.Linq;
using System.Threading.Tasks;
 
static class Program
{
static void Main()
{
  string inputVal = Console.ReadLine();
  int val1 = int.Parse(inputVal.Substring(0, 2));
  int val2 = int.Parse(inputVal.Substring(2, 2));
  bool mayMonthVal1 = val1 >= 1 && val1 <= 12;
  bool mayMonthVal2 = val2 >= 1 && val2 <= 12;

  string ret = "";
  //NA
  if (val1 < 0)
    ret = "NA";
  else if (val1 == 0 && val2 == 0)
    ret = "NA";
  else if (val1 == 0 && mayMonthVal2)
    ret = "YYMM";
  else if (val2 == 0 && mayMonthVal1)
    ret = "MMYY";
  else if (mayMonthVal1 && mayMonthVal2)
    ret = "AMBIGUOUS";
  else if (mayMonthVal1)
    ret = "MMYY";
  else if (mayMonthVal2)
    ret = "YYMM";
  else
    ret = "NA";
  Console.WriteLine(ret);
}
}