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: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func getNextLine(scanner *bufio.Reader) string {
	var buffer string
	for {
		line, isPrefix, _ := scanner.ReadLine()
		buffer += string(line)
		if isPrefix == false {
			break
		}
	}
	return buffer
}

func getIntList(scanner *bufio.Reader) []int {
	list := strings.Split(getNextLine(scanner), " ")
	l := len(list)
	result := make([]int, l)
	for i := 0; i < l; i++ {
		result[i], _ = strconv.Atoi(list[i])
	}
	return result
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := bufio.NewReader(fp)

	s := getNextLine(scanner)
	fmt.Println(chokudai(s))
}

func chokudai(s string) string {
	part1, _ := strconv.Atoi(s[0:2])
	part2, _ := strconv.Atoi(s[2:4])
	if part1 == 0 || part2 == 0 {
		return "NA"
	}
	if part1 > 12 && part2 > 12 {
		return "NA"
	}
	if part1 > 12 && part2 <= 12 {
		return "YYMM"
	}
	if part2 > 12 && part1 <= 12 {
		return "MMYY"
	}
	return "AMBIGUOUS"
}