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::cmp;
use std::collections::BinaryHeap;
use std::collections::HashMap;
use std::collections::HashSet;

fn read_line() -> String {
    let mut buf = String::new();
    io::stdin().read_line(&mut buf).ok();
    buf
}

fn parse(s: &str) -> usize {
    if s == "00" {
        0
    } else {
        s.parse().unwrap()
    }
}


fn main() {
    let s = read_line();
    let s = s.trim();

    let (yy, mm) = s.split_at(2);

    let y = parse(yy);
    let m = parse(mm);

    let mut valid_yymm = false;
    let mut valid_mmyy = false;

    if m >= 1 && m <= 12 {
        valid_yymm = true;
    }
    if y >= 1 && y <= 12 {
        valid_mmyy = true;
    }

    if valid_mmyy && valid_yymm {

        println!("AMBIGUOUS");
    } else if valid_yymm {
        println!("YYMM");
    } else if valid_mmyy {
        println!("MMYY");
    } else {
        println!("NA");
    }
}