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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
	"io"
	"os"
	"regexp"
)

func solve(w io.Writer, r io.Reader) {
	var S string
	fmt.Scan(&S)
	amb := regexp.MustCompile("^(0[1-9]|1[0-2])(0[1-9]|1[0-2])$")
	mmyy := regexp.MustCompile("^(0[1-9]|1[0-2])")
	yymm := regexp.MustCompile("(0[1-9]|1[0-2])$")

	var ans string
	if amb.MatchString(S) {
		ans = "AMBIGUOUS"
	} else if mmyy.MatchString(S) {
		ans = "MMYY"
	} else if yymm.MatchString(S) {
		ans = "YYMM"
	} else {
		ans = "NA"
	}
	
	fmt.Fprintln(w, ans)
}

func main() {
	solve(os.Stdout, os.Stdin)
}