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"
  "os"
  "bufio"
  "strconv"
)

func main() {
  sc := bufio.NewScanner(os.Stdin)
  sc.Split(bufio.ScanLines)

  sc.Scan()
  s := sc.Text()

  yymm := false
  mmyy := false

  a, _ := strconv.Atoi(s[:2])
  if a > 0 && a < 13 {
    mmyy = true
  }
  a, _ = strconv.Atoi(s[2:])
  if a > 0 && a < 13 {
    yymm = true
  }

  if yymm && mmyy {
    fmt.Println("AMBIGUOUS")
  } else if yymm {
    fmt.Println("YYMM")
  } else if mmyy {
    fmt.Println("MMYY")
  } else {
    fmt.Println("NA")
  }
}