var defaultEmptyOK = false
// VARIABLE DECLARATIONS

// whitespace characters
var whitespace = " \t\n\r";

function isEmpty(s) {
	var i;
	var space = ' \r\n';
	if ((s == null) || (s.length < 1)) return true;
		for (i = 0; i < s.length; i++) {
		var ch = s.charAt(i);
		if (space.indexOf(ch) == -1) return false;
	}

	return true;
}



//**************************************************************************
// Returns true if string s is empty or 
// whitespace characters only.
function isWhitespace (s)
{   var i;
	
    // Is s empty?
    if (isEmpty(s)) return true;

    // Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    return true;
}



//**************************************************************************
// isEmail (STRING s [, BOOLEAN emptyOK])
// 
// Email address must be of form a@b.c -- in other words:
// * there must be at least one character before the @
// * there must be at least one character before and after the .
// * the characters @ and . are both required
// * there may be only 1 @.
// * there may not be any spaces.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.
function isEmail (s)
{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
   
    // is s whitespace?
    if (isWhitespace(s)) return false;
    
    // there must be >= 1 character before @, so we
    // start looking at character position 1 
    // (i.e. second character)
    var i = 1;
    var sLength = s.length;

    // look for @
    while ((i < sLength) && (s.charAt(i) != "@"))
    { i++
    }

	// Found the @.  Skip it and the character after it (must have
	// at least 1 character before the period.
    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;

    // look for .
    while ((i < sLength) && (s.charAt(i) != "."))
    { i++
    }

    // there must be at least one character after the .
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;

	// there may be only 1 @.
	if (s.indexOf('@') != s.lastIndexOf('@')) return false;
	
	// there may not be any spaces.
	if (s.indexOf(' ') != -1) return false;
    else return true;
}


//**************************************************************************
// Returns true if character c is a digit 
// (0 .. 9).
function isDigit (c)
{   return ((c >= "0") && (c <= "9"))
}







// isMonth (STRING s [, BOOLEAN emptyOK])
// 
// isMonth returns true if string s is a valid 
// month number between 1 and 12.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isMonth (s)
{   if (isEmpty(s)) 
       if (isMonth.arguments.length == 1) return defaultEmptyOK;
       else return (isMonth.arguments[1] == true);
    return isIntegerInRange (s, 1, 12);
}



// isDay (STRING s [, BOOLEAN emptyOK])
// 
// isDay returns true if string s is a valid 
// day number between 1 and 31.
// 
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isDay (s)
{   if (isEmpty(s)) 
       if (isDay.arguments.length == 1) return defaultEmptyOK;
       else return (isDay.arguments[1] == true);   
    return isIntegerInRange (s, 1, 31);
}



// daysInFebruary (INTEGER year)
// 
// Given integer argument year,
// returns number of days in February of that year.

function daysInFebruary (year)
{   // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (  ((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0) ) ) ? 29 : 28 );
}






// isNonnegativeInteger (STRING s [, BOOLEAN emptyOK])
// 
// Returns true if string s is an integer >= 0.
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isNonnegativeInteger (s)
{   var secondArg = defaultEmptyOK;

    if (isNonnegativeInteger.arguments.length > 1)
        secondArg = isNonnegativeInteger.arguments[1];

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a number >= 0

    return (isSignedInteger(s, secondArg)
         && ( (isEmpty(s) && secondArg)  || (parseInt (s) >= 0) ) );
}

	
function getCentury(year) {
	if (year < 10) {
		return '200' + year;}
	if (year < 30) {
		return '20' + year;}
	if (year >= 30 & year <= 99) {
		return '19' + year;}
	return year;
}