import tio.*;

/**
 * LeapYear.java - 
 *   Given a year it is calculated if that year
 *   is a leap year.  Leap year calculation was 
 *   one of the big issues in the Y2K problem.  
 *
 *   The specific rules for determining leap years are:
 *
 *     1) If a year is divisible by 4 it is a
 *        leap year if #2 does not apply.
 *     2) If a year is divisible by 100 it is 
 *        not a leap year unless #3 applies.
 *     3) If a year is divisible by 400 it is
 *        a leap year.
 *
 *   Many programs are believed to have incorrect 
 *   logic for computing leap years due to the 
 *   omission of #2 and/or #3.
 *
 *   The handling of the 1900's vs. 2000's is
 *   done by a technique called windowing.  This
 *   is a common strategy that was used to "solve"
 *   the Y2K problem.  However, the problem has
 *   realy just been postponed by some number
 *   of years.
 * 
 *   NOTE: This program ignores changes in the 
 *         Gregorian calendar and only applies
 *         correctly to dates after 1582.
 *
 * @author Grant William Braught
 * @author Dickinson College
 * @version 9/17/2001
 */

public class LeapYear {
    public static void main (String[] args) {

	// The year to check for leapiness.
	int theYear;

	// Get the year.
	// For now we'll assume they enter a reasonable value.
	System.out.print("Enter the year: ");
	theYear = Console.in.readInt();

	// Check for a 2 digit year and adjust the year
	// using a windowing technique.  If the date has
	// more than 2 digits we'll assume it is a complete
	// year.
	if (theYear < 100) {
	    // If the year is greater than 40 assume it
	    // is from 1900's.  If the year is less than
	    // 40 assume it is from 2000's.
	    if (theYear > 40) {
		theYear = theYear + 1900;
	    }
	    else {
		theYear = theYear + 2000;
	    }
	}

	// Is theYear Divisible by 4?
	if (theYear % 4 == 0) {

	    // Is theYear Divisible by 4 but not 100?
	    if (theYear % 100 != 0) {
		System.out.println(theYear + " is a leap year.");
	    }
	    // Is theYear Divisible by 4 and 100 and 400?
	    else if (theYear % 400 == 0) {
		System.out.println(theYear + " is a leap year.");
	    }
	    // It is Divisible by 4 and 100 but not 400!
	    else {
		System.out.println(theYear + " is not a leap year.");
	    }
	}
	// It is not divisible by 4.
	else {
	    System.out.println(theYear + " is not a leap year.");
	}
    }
}