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"
func main(){
    var s string
    fmt.Scan(&s)
    str := []byte(s)
    var yy, mm int
    for i, _ := range str {
        str[i]-= 48
    }
    yy = int(str[0]*10 + str[1])
    mm = int(str[2]*10 + str[3])
    if yy<13&&yy>0&&mm<13&&mm>0{
        fmt.Println("AMBIGUOUS")
    }else if yy<13&&yy>0{
        fmt.Println("MMYY")
    }else if mm<13&&mm>0{
        fmt.Println("YYMM")
    }else{
        fmt.Println("NA")
    }
}