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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#include <regex>
using namespace std;

int main(void) {
  string S;
  cin >> S;
  smatch match;
  bool isYYMM = false;
  bool isMMYY = false;
  if (regex_match(S, match,
                  regex("(01|02|03|04|05|06|07|08|09|10|11|12)+[0-9]{2}"))) {
    isMMYY = true;
  }
  if (regex_match(S, match,
                  regex("[0-9]{2}(01|02|03|04|05|06|07|08|09|10|11|12)+"))) {
    isYYMM = true;
  }

  if (isYYMM && isMMYY) {
    cout << "AMBIGUOUS" << endl;
    return 0;
  }

  if (isYYMM) {
    cout << "YYMM" << endl;
    return 0;
  }

  if (isMMYY) {
    cout << "MMYY" << endl;
    return 0;
  }

  cout << "NA" << endl;

  return 0;
}