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 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

bool isMonth(int m)
{
	if( 1 <= m && m <= 12 )
	{
		return true;
	}
	return false;
}

bool isYYMM(int t, int b)
{
	if( t <= 0 ) return false;

	return isMonth(b);
}

bool isMMYY(int t, int b)
{
	if( b <= 0 ) return false;

	return isMonth(t);
}

void checkFormat(int t, int b)
{
	if( isYYMM(t, b) && isMMYY(t, b) )
		printf("AMBIGUOUS");
	else if( isYYMM(t, b) )
		printf("YYMM");
	else if( isMMYY(t, b) )
		printf("MMYY");
	else
		printf("NA");
}

void main(void)
{
	char str[8];
	char top[4], buttom[4];
	int t, b;

	scanf("%s", str);

	t = (str[0] - '0') * 10 + str[1] - '0';
	b = (str[2] - '0') * 10 + str[3] - '0';

	printf("%s = %02d %02d\n", str, t, b);

	checkFormat(t, b);
}