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 s=Console.ReadLine();
    int a=Convert.ToInt32(s[0].ToString()+s[1].ToString());
    int b=Convert.ToInt32(s[2].ToString()+s[3].ToString());
  
    string answ="";
  if(a<=0){
   if((b<=0)||(b>12)){
     answ="NA";
   }else{
     answ="YYMM";
   }
  }else if(a<=12){
    if((b<=12)&&(b>0)){
     answ="AMBIGUOUS";
    }else{
      answ="MMYY";
    }    
  }else if(a>12){
    if((b>12)||(b<=0)){
      answ="NA";
    }else{
      answ="YYMM";
    }
  }
    
    Console.WriteLine(answ);
}
}