public class Date
{
  protected int year;
  protected int month;
  protected int day;
  public static final int MINYEAR = 1583;

  // Constructor
  public Date(int newMonth, int newDay, int newYear)
  {
    month = newMonth;
    day = newDay;
    year = newYear;
   }

  // Observers
  public int getYear()
  {
    return year;
  }

  public int getMonth()
  {
    return month;
  }

  public int getDay()
  {
    return day;
  }

  public int lilian()
  {
    // Returns the Lilian Day Number of this date.
    // Precondition: This Date is a valid date after 10/14/1582.
    //
    // Computes the number of days between 1/1/0 and this date as if no calendar
    // reforms took place, then subtracts 578,100 so that October 15, 1582 is day 1.
    
    final int subDays = 578100;  // number of calculated days from 1/1/0 to 10/14/1582

    int numDays = 0;

    // Add days in years.
    numDays = year * 365;

    // Add days in the months.
    if (month <= 2)
      numDays = numDays + (month - 1) * 31;
    else
      numDays = numDays + ((month - 1) * 31) - ((4 * (month-1) + 27) / 10);

    // Add days in the days.
    numDays = numDays + day;

    // Take care of leap years.
    numDays = numDays + (year / 4) - (year / 100) + (year / 400);

    // Handle special case of leap year but not yet leap day.
    if (month < 3)
    {
        if ((year % 4) == 0)   numDays = numDays - 1;
        if ((year % 100) == 0) numDays = numDays + 1;
        if ((year % 400) == 0) numDays = numDays - 1;
      }

    // Subtract extra days up to 10/14/1582.
    numDays = numDays - subDays;
    return numDays;
  }

  public String toString()
  // Returns this date as a String.
  {
    return(month + "/" + day + "/" + year);
  }

}

import java.util.Scanner;

public class DaysBetween
{
  public static void main(String[] args)
  {
    Scanner conIn = new Scanner(System.in);
    int day, month, year;
        
    System.out.println("Enter two 'modern' dates: month day year");
    System.out.println("For example, January 12, 1954, would be: 1 12 1954");
    System.out.println();
    System.out.println("Modern dates occur after " + Date.MINYEAR + ".");
    System.out.println();
        
    System.out.println("Enter the first date:");
    month = conIn.nextInt();
     day = conIn.nextInt();
    year = conIn.nextInt();
    Date date1 = new Date(month, day, year);
        
    System.out.println("Enter the second date:");
    month = conIn.nextInt();
    day = conIn.nextInt();
    year = conIn.nextInt();
    Date date2 = new Date(month, day, year);
        
    if ((date1.getYear() <= Date.MINYEAR)
        ||
         (date2.getYear() <= Date.MINYEAR))
      System.out.println("You entered a 'pre-modern' date.");
    else
    {
      System.out.println("The number of days between");
      System.out.print(date1);
      System.out.print(" and ");
      System.out.print(date2);
      System.out.print(" is ");
      System.out.println(Math.abs(date1.lilian() - date2.lilian()));
    }
  }
}