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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.time.Instant;
import java.util.*;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

public class Main {
	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);
		String S = sc.next();

		int f = Integer.parseInt(S.substring(0, 2));
		int l = Integer.parseInt(S.substring(2, 4));

		boolean fBool = 0 < f && f < 13;
		boolean lBool = 0 < l && l < 13;

		if(fBool && lBool){
			System.out.println("AMBIGUOUS");
		} else if(fBool && !lBool){
			System.out.println("MMYY");
		} else if(!fBool && lBool){
			System.out.println("YYMM");
		} else {
			System.out.println("NA");
		}

	}
}