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)

use std::io;
use std::io::BufRead;

fn main() {
    let stdin = io::stdin();
    let mut stdin = stdin.lock();

    let s = {
        let mut input = String::new();
        stdin.read_line(&mut input).unwrap();
        input.trim().to_string()
    };

    let a = s[0..2].parse::<i32>().unwrap();
    let b = s[2..4].parse::<i32>().unwrap();

    match ( is_mounth(a), is_mounth(b) ) {
        (true, true) => println!("AMBIGUOUS"),
        (true, false) => println!("MMYY"),
        (false, true) => println!("YYMM"),
        (false, false) => println!("NA"),
    }
}

fn is_mounth( n: i32 ) -> bool {
    n > 0 && n < 13
}