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 Rust (1.15.1) (judge verdict: Accepted)

fn is_yy(n: usize) -> bool {
    n == 0 || n > 12
}

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();

    let s01 = &buf[..2];
    let s02 = &buf[2..];
    let n01: usize = s01.parse().unwrap();
    let n02: usize = s02.trim().parse().unwrap();

    let ans = match (is_yy(n01), is_yy(n02)) {
        (true, true) => "NA",
        (true, false) => "YYMM",
        (false, true) => "MMYY",
        (false, false) => "AMBIGUOUS",
    };

    println!("{}", ans);
}