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: Wrong Answer)

import java.net.StandardSocketOptions;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
    MyScanner sc = new MyScanner();
    Scanner sc2 = new Scanner(System.in);
    long start = System.currentTimeMillis();
    long fin = System.currentTimeMillis();
    final int MOD = 1000000007;
    int[] dx = {1, 0, 0, -1};
    int[] dy = {0, 1, -1, 0};

    void run() {
        String S = sc.next();
        int a = Integer.valueOf(S.substring(0, 2));
        int b = Integer.valueOf(S.substring(2, 4));

        int fa = 0;
        int fb = 0;

        if (a >= 13) fa = 1;
        else if(a > 0) fa = 2;
        if (b >= 13) fb = 1;
        else if(b > 0) fb = 2;

        String res = "YYMM";

        if( fa == 0 || fb == 0) {
            res = "NA";
        } else if(fa == 2 && fb == 2) {
            res = "AMBIGUOUS";
        } else if (fa == 2 && fb == 1) {
            res = "MMYY";
        }
        System.out.println(res);
    }

    public static void main(String[] args) {
        new Main().run();
    }

    void debug(Object... o) {
        System.out.println(Arrays.deepToString(o));
    }


    void debug2(char[][] array) {
        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
                System.out.print(array[i][j]);
            }
            System.out.println();
        }
    }

    boolean inner(int h, int w, int limH, int limW) {
        return 0 <= h && h < limH && 0 <= w && w < limW;
    }

    void swap(int[] x, int a, int b) {
        int tmp = x[a];
        x[a] = x[b];
        x[b] = tmp;
    }

    // find minimum i (k <= a[i])
    int lower_bound(int a[], int k) {
        int l = -1;
        int r = a.length;
        while (r - l > 1) {
            int mid = (l + r) / 2;
            if (k <= a[mid]) r = mid;
            else l = mid;
        }
        // r = l + 1
        return r;
    }

    // find minimum i (k < a[i])
    int upper_bound(int a[], int k) {
        int l = -1;
        int r = a.length;
        while (r - l > 1) {
            int mid = (l + r) / 2;
            if (k < a[mid]) r = mid;
            else l = mid;
        }
        // r = l + 1
        return r;
    }

    long gcd(long a, long b) {
        return a % b == 0 ? b : gcd(b, a % b);
    }

    long lcm(long a, long b) {
        return a * b / gcd(a, b);
    }

    boolean palindrome(String s) {
        for (int i = 0; i < s.length() / 2; i++) {
            if (s.charAt(i) != s.charAt(s.length() - 1 - i)) {
                return false;
            }
        }
        return true;
    }

    class MyScanner {
        int nextInt() {
            try {
                int c = System.in.read();
                while (c != '-' && (c < '0' || '9' < c))
                    c = System.in.read();
                if (c == '-')
                    return -nextInt();
                int res = 0;
                do {
                    res *= 10;
                    res += c - '0';
                    c = System.in.read();
                } while ('0' <= c && c <= '9');
                return res;
            } catch (Exception e) {
                return -1;
            }
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        String next() {
            try {
                StringBuilder res = new StringBuilder("");
                int c = System.in.read();
                while (Character.isWhitespace(c))
                    c = System.in.read();
                do {
                    res.append((char) c);
                } while (!Character.isWhitespace(c = System.in.read()));
                return res.toString();
            } catch (Exception e) {
                return null;
            }
        }

        int[] nextIntArray(int n) {
            int[] in = new int[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextInt();
            }
            return in;
        }

        int[][] nextInt2dArray(int n, int m) {
            int[][] in = new int[n][m];
            for (int i = 0; i < n; i++) {
                in[i] = nextIntArray(m);
            }
            return in;
        }

        double[] nextDoubleArray(int n) {
            double[] in = new double[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextDouble();
            }
            return in;
        }

        long[] nextLongArray(int n) {
            long[] in = new long[n];
            for (int i = 0; i < n; i++) {
                in[i] = nextLong();
            }
            return in;
        }

        char[][] nextCharField(int n, int m) {
            char[][] in = new char[n][m];
            for (int i = 0; i < n; i++) {
                String s = sc.next();
                for (int j = 0; j < m; j++) {
                    in[i][j] = s.charAt(j);
                }
            }
            return in;
        }
    }
}