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>

#define fastio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define endl "\n"

using namespace std;
using ll = long long;

const ll MOD = 1000000007LL; // = 10^9 + 7
const double PI = 3.14159265358979;

void solve()
{
  int s;
  cin >> s;

  int front = s / 100;
  int back = s % 100;

  bool yymm = (front < 100) && (0 < back) && (back <= 12);
  bool mmyy = (0 < front) && (front <= 12) && (back < 100);

  if (yymm && mmyy) cout << "AMBIGUOUS";
  else if (yymm) cout << "YYMM";
  else if (mmyy) cout << "MMYY";
  else cout << "NA";
}

int main()
{
	fastio;
	solve();

	return 0;
}