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)

#[macro_use]
mod reader {
    use std;
    macro_rules! read_line((  ) => {
                           {
                           let mut input = String :: new (  ) ; std :: io ::
                           stdin (  ) . read_line ( & mut input ) . unwrap (
                           ) ; input } } ;);
    pub fn read_trim() -> String { read_line!().trim().to_owned() }
}
use reader::*;
fn main() {
    let input = read_trim();
    let former: u32 = input[..2].parse().ok().unwrap();
    let latter: u32 = input[2..].parse().ok().unwrap();
    if 1 <= former && former <= 12 {
        if 1 <= latter && latter <= 12 {
            println!("AMBIGUOUS");
        } else { println!("MMYY"); }
    } else {
        if 1 <= latter && latter <= 12 {
            println!("YYMM")
        } else { println!("NA") }
    }
}