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>

int isM(int a)
{
  return 1 <= a && a <= 12;
}

int main(void)
{
  char S[10];
  scanf("%s", S);
  int a = (S[0]-'0')*10+S[1]-'0';
  int b = (S[2]-'0')*10+S[3]-'0';
  if(isM(a) || isM(b)){
    if(isM(a) && isM(b))
      printf("%s\n", "AMBIGUOUS");
    else if(isM(a))
      printf("%s\n", "MMYY");
    else
      printf("%s\n", "YYMM");
  }
  else
    printf("%s\n", "NA");
  return 0;
}