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.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        sc.close();
        String S1 = S.substring(0, 2);
        String S2 = S.substring(2, 4);
        if (isYYMM(S1, S2) && isMMYY(S1, S2)) {
            System.out.println("AMBIGUOUS");
        } else if (isYYMM(S1, S2)) {
            System.out.println("YYMM");
        } else if (isMMYY(S1, S2)) {
            System.out.println("MMYY");
        } else {
            System.out.println("NA");
        }
    }
    public static boolean isYear(String S) {
        int yy = Integer.valueOf(S);
        if (0 <= yy && yy <= 99) {
            return true;
        }
        return false;
    }
    public static boolean isMonth(String S) {
        int mm = Integer.valueOf(S);
        if (1 <= mm && mm <= 12) {
            return true;
        }
        return false;
    }
    public static boolean isYYMM(String S, String T) {
        if (isYear(S) && isMonth(T)) {
            return true;
        }
        return false;
    }
    public static boolean isMMYY(String S, String T) {
        if (isMonth(S) && isYear(T)) {
            return true;
        }
        return false;
    }
}