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<stdio.h>

static char CheckFormat(int a_iS);

int main(void) {
	int		iS;
	char	cFormat;	
	//長さ4の数字列を入力
	scanf("%d", &iS);
	
	//入力された値がYYMM,MMYYフォーマットのどちらかと考えられるか求める
	cFormat = CheckFormat(iS);
	//求めた結果を出力
	switch (cFormat){
	case 1:
		printf("AMBIGUOUS\n");
		break;
	case 2:
		printf("YYMM\n");
		break;
	case 3:
		printf("MMYY\n");
		break;
	case 4:
		printf("NA\n");
		break;

	default:
		break;
	}
	return 0;
}

/*****************
*	YYMM,MMYYのどちらのフォーマットに合うか確認する関数
*	a_iS 入力された長さ4の数字列
*/

static char CheckFormat(int a_iS) {
	int iHigh2, iLow2;
	int j;

	iHigh2	= a_iS / 100;
	iLow2	= a_iS % 100;

	//どちらの可能性も存在するとき
	if ((1 <= iHigh2 && iHigh2 <= 12) && (1 <= iLow2 && iLow2 <= 12)) {
		j = 1;
	}
	//YYMMフォーマットのとき
	else if (1 <= iLow2 && iLow2 <= 12) {
		j = 2;
	}
	//MMYYフォーマットのとき
	else if (1 <= iHigh2 && iHigh2 <= 12) {
		j = 3;
	}
	//どちらでもないとき
	else {
		j = 4;
	}
	return(j);
}