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 (Clang 3.8.0) (judge verdict: Accepted)

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

int main() {
  int i, j;
  char prev[3];
  char after[3];
  int prev_num, after_num;

  scanf("%c", &prev[0]);
  scanf("%c", &prev[1]);
  scanf("%c", &after[0]);
  scanf("%c", &after[1]);
  prev[2] = '\0';
  after[2] = '\0';

  prev_num = atoi(prev);
  after_num = atoi(after);

  int p_f, a_f;

  if(prev_num <= 12 && prev_num >= 1){
    p_f = 1;
  }
  else{
    p_f = 0;
  }
  if(after_num <= 12 && after_num >= 1){
    a_f = 1;
  }
  else{
    a_f = 0;
  }

  if (a_f && p_f){
    printf("AMBIGUOUS");
  }
  else if (p_f){
    printf("MMYY");
  }
  else if (a_f) {
    printf("YYMM");
  }
  else{
    printf("NA");
  }

  return 0;
}