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.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String S = sc.next();
        sc.close();

        String firstString = S.substring(0, 2);
        String lastString = S.substring(2, 4);

        String result = "NA";
        int count = 0;
        if (isYY(firstString)) {
            if (isMM(lastString)) {
                result = "YYMM";
                count++;
            }
        }
        if (isMM(firstString)) {
            if (isYY(lastString)) {
                result = "MMYY";
                count++;
            }
        }
        if (count == 2) {
            result = "AMBIGUOUS";
        }
        System.out.println(result);
    }
    public static boolean isYY(String string) {

        boolean flag = false;
        if (string.matches("[0-9]{2}")) {
            flag = true;
        }
        return flag;
    }
    public static boolean isMM(String string) {

        boolean flag = false;
        if (string.matches("0[1-9]{1}") || string.matches("1[0-2]{1}")) {
            flag = true;
        }
        return flag;
    }
}