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)

// #[warn(dead_code)]
// const TOP: u64 = 1000000007;

fn main() {
	let text = {
		use std::io::Read;
		let mut s = String::new();
		std::io::stdin().read_to_string(&mut s).unwrap();
		s
	};

	let word = text.trim();

	let first: u32 = word.chars().take(2).collect::<String>().parse().unwrap();
	let last: u32 = word
		.chars()
		.skip(2)
		.take(2)
		.collect::<String>()
		.parse()
		.unwrap();

	if 1 <= first && first <= 12 {
		if 1 <= last && last <= 12 {
			println!("AMBIGUOUS");
		} else {
			println!("MMYY");
		}
	} else {
		if 1 <= last && last <= 12 {
			println!("YYMM");
		} else {
			println!("NA");
		}
	}

	// println!("{} {}", first, last);
}