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>

using namespace std;
typedef long long ll;

#define REP(i, n) for (ll i = 0; i < (n); i++)
#define REPR(i, n) for (ll i = (n); i >= 0; i--)
#define FOR(i, m, n) for (ll i = (m); i < (n); i++)
#define FORR(i, m, n) for (ll i = (m); i >= (n); i--)
#define INF 1e9
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((ll)(x).size())
#define SORT(x) sort((x).begin(), (x).end())
#define dump(x) cerr << #x << " = " << (x) << endl
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" \
                      << " " << __FILE__ << endl

int main(int argc, char const *argv[])
{
    string s;
    cin >> s;
    ll s0 = (s[0] - '0');
    ll s1 = (s[1] - '0');
    ll s2 = (s[2] - '0');
    ll s3 = (s[3] - '0');
    ll a = s0 * 10 + s1;
    ll b = s2 * 10 + s3;
    // bool a_year = true;
    bool a_month = true;
    // bool b_year = true;
    bool b_month = true;
    if (a < 1 || a > 12)
        a_month = false;
    if (b < 1 || b > 12)
        b_month = false;
    if (a_month && b_month)
        cout << "AMBIGUOUS" << endl;
    else if (!a_month && b_month)
        cout << "YYMM" << endl;
    else if (a_month && !b_month)
        cout << "MMYY" << endl;
    else
        cout << "NA" << endl;
    return 0;
}