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<stdbool.h>

#define NUM(a) (a - '0')

bool month(char *str) {
    int num = NUM(str[0])*10 + NUM(str[1]);
    if(num > 0 && num <= 12) { return true; }
    return false;
}

int main(void){
    char *str = (char*)malloc(6*sizeof(char));
    scanf("%s", str);
    bool my = month(str), ym = month(str+2);
    if(my && ym) { printf("AMBIGUOUS\n"); }
    else if (my) { printf("MMYY\n"); }
    else if (ym) { printf("YYMM\n"); }
    else { printf("NA\n"); }
    free(str);
    return 0;
}