import java.util.regex.*;;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	 private static Pattern PATTERN =
        Pattern.compile("^(\\d|[12]\\d|3[01])$");
 
	public static void main (String[] args) throws java.lang.Exception
	{
      String [] numbers = {"0", "03", "5", "10", "31", "32"};
      for (String number : numbers) {
         Matcher matcher = PATTERN.matcher(number);
         if (matcher.matches()) {
            System.out.println("Matches for " + number + " : " + matcher.group(1) );
         }
         else {
           System.out.println("No matches for " + number);
         }
      }
   }
 
}

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