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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)

int main() {
  string s;
  cin >> s;
  string L = s.substr(0, 2);
  string R = s.substr(2, 2);
  int l = 10 * (L[0] - '0') + (L[1] - '0');
  int r = 10 * (R[0] - '0') + (R[1] - '0');
  if (1 <= l && l <= 12 && 1 <= r && r <= 12) {
    cout << "AMBIGUOUS" << endl;
    return 0;
  }
  if (1 <= l && l <= 12 && 0 <= r && r <= 99) {
    cout << "MMYY" << endl;
    return 0;
  }
  if (0 <= l && l <= 99 && 1 <= r && r <= 12) {
    cout << "YYMM" << endl;
    return 0;
  }
  cout << "NA" << endl;
  return 0;
}