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 main() {
    let v: Vec<char> = {
        let s = read::<String>();
        s.chars().into_iter().collect()
    };
    let x = ((v[0] as u8) - b'0') * 10 + (v[1] as u8) - b'0';
    let y = ((v[2] as u8) - b'0') * 10 + (v[3] as u8) - b'0';
    let yymm = 1 <= y && y <= 12;
    let mmyy = 1 <= x && x <= 12;
    let ret = if yymm && mmyy {
        "AMBIGUOUS"
    } else if yymm && !mmyy {
        "YYMM"
    } else if !yymm && mmyy {
        "MMYY"
    } else {
        "NA"
    };
    println!("{}", ret);
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().parse().ok().unwrap()
}