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: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>

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

//prototype declaration
int getint();
long long getllint();
double getdint();
char getch();
void setstring(char *s);
void showint(int i);
void showllint(long long i);
void showdint(double i);
void showchar(char c);
void showstring(char *s);

int myPower(int a, int n) { // aのn乗の計算
	int x = 1;
	while (n > 0) { // 全てのbitが捨てられるまで
		if ( n & 1) { // 一番右のbitが１のとき
			x *= a;
		}
		a *= a;
		n >>= 1; // bit全体を右に1つシフトして一番右を捨てる
	}
	return x;
}

int min(int a, int b) {
	return a < b ? a : b;
}

int main(void) {
	char s[4];
	scanf("%s", s);
	int i;
	int yy = 0, mm = 0;
	if (s[0] == '0' && s[1] != '0') {
		mm = 1;
	}
	if (s[0] == '1') {
		if (s[1] == '0' || s[1] == '1' || s[1] == '2') {
			mm = 1;
		}
	}
	if (s[2] == '0' && s[3] != '0') {
		yy = 1;
	}
	if (s[2] == '1') {
		if (s[3] == '0' || s[3] == '1' || s[3] == '2') {
			yy = 1;
		}
	}

	if (mm == 1 && yy == 1) {
		showstring("AMBIGUOUS");
	} else if (mm == 1 && yy == 0) {
		showstring("MMYY");
	} else if (mm == 0 && yy == 1) {
		showstring("YYMM");
	} else {
		showstring("NA");
	}
	return 0;
}

int getint() {
	int i;
	scanf("%d", &i);
	return i;
}

long long getllint() {
	long long i;
	scanf("%lld", &i);
	return i;
}

double getdint() {
	double i;
	scanf("%lf", &i);
	return i;
}

char getch() {
	char c;
	scanf("%c", &c);
	return c;
}

void setstring(char *s) {
	scanf("%s", s);
}

void showint(int i) {
	printf("%d\n", i);
}

void showllint(long long i) {
	printf("%lld\n", i);
}

void showdint(double i) {
	printf("%lf\n", i);
}

void showchar(char c) {
	printf("%c\n", c);
}

void showstring(char *s) {
	printf("%s\n", s);
}