import java.io.*;
import java.text.*;
import java.util.*;

public class FindAge
{
     public static void main(String args[])
     {
          Person person = new Person ();
          person.getData();
          person.displayData();
     }
} // FindAge

/* The Person class gets the current date using a GregorianCalendar class, reads in the birth date using a StringTokenizer, checks to see that the read in date is valid, and then calculates and displays the age. */
class Person
{
     private String name;
     private int currentYear, currentMonth, currentDay, birthYear, birthMonth, birthDay;
 
     void getData()
     {
          getCurrentDate (); // Gets the current date using a GregorianCalendar class.
          String dataString;
          StringTokenizer tokenizer;
          BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
          try
          {
               System.out.println("Enter name, birth day, birth month and birth year on a single line.");
               dataString = stdin.readLine();
               tokenizer = new StringTokenizer(dataString);

               // Use the tokens to get the name and birthday of a person.
               name = tokenizer.nextToken();
               birthDay = Integer.parseInt (tokenizer.nextToken ());
               birthMonth = Integer.parseInt (tokenizer.nextToken ());
               birthYear = Integer.parseInt (tokenizer.nextToken ());

               // Verify that the date read in is valid.
               boolean validDate = verifyDate (birthDay, birthMonth, birthYear, currentYear);
               if (!validDate) System.out.println ("Date invalid");
          }catch (NumberFormatException e){System.out.println("Number Format Error");}
          catch (IOException e){System.out.println("IO Error");}
     }//End getData
 
     // Use a GregorianCalendar class to get the current date.
     private void getCurrentDate ()
     {
          GregorianCalendar now = new GregorianCalendar ();
          currentDay = now.get (Calendar.DATE);
          currentMonth = now.get (Calendar.MONTH);
          currentMonth ++;
          currentYear = now.get (Calendar.YEAR);
     } // getCurrentDate

     // Use the current date and the birth date to calculate a person’s age.
     private int calculateAge ()
     {
          int age = currentYear - birthYear;
          if (currentMonth < birthMonth) age --;
          else
              if ((currentMonth == birthMonth) && (currentDay < birthDay)) age --;
          return age;
     } // calculateAge
 
     //Display the age on the screen.
     void displayData()
     {
          int age = calculateAge ();
          System.out.println (name + "'s age is " + age);
     } //End displayData

     // Verify that the date given is a valid date.
     private boolean verifyDate (int day, int month, int year, int currentYear)
     {
          if (year > currentYear)  return false;
          else
          if ((month <= 0) || (month > 12) || (day <= 0) || (day > 31)) return false;
          else
          if ((month == 2) && (day > 29)) return false; // February
          else // April, June, September, November
          if (((month == 4) || (month == 6) || (month == 9) || (month == 11) ) && (day > 30)) return false;
          else return true;
     } // verifyDate
}//end class Person