function selectMonth() {
		var objSelectDay = document.getElementById("birthday-day");
		var iMonth = parseInt(document.getElementById("birthday-month").value);
		var iYear = parseInt(document.getElementById("birthday-year").value);
		
		var iDays = getCountOfDays(iYear, iMonth);
		
		buildSelectDay(iDays, objSelectDay);
	}
	
	function selectYear() {
		var objSelectDay = document.getElementById("birthday-day");
		var iMonth = parseInt(document.getElementById("birthday-month").value);
		var iYear = parseInt(document.getElementById("birthday-year").value);
		
		var iDays = getCountOfDays(iYear, iMonth);
		buildSelectDay(iDays, objSelectDay);
	}
		
	function getCountOfDays(iYear, iMonth) {
		if (!isNaN(iYear) && !isNaN(iMonth)){
			iDays = new Date(iYear, iMonth, 0).getDate();
		} else if (!isNaN(iYear)) {
			iDays = new Date(iYear, 1, 0).getDate();
		} else if (!isNaN(iMonth)) {
			iDays = new Date(2010, iMonth, 0).getDate();
		}
		return iDays;
	}
	
	function deleteDays()
	{
		var objSelectDay = document.getElementById("birthday-day");
		while( objSelectDay.length != 1 )
		{
			objSelectDay.options[objSelectDay.length-1] = null;
		}
	}	
	
	function buildSelectDay(iDays, objSelectDay) 
	{
		iSelIndex = objSelectDay.selectedIndex;
		deleteDays();
		
		for( iIndex = 1; iIndex <= iDays; iIndex++ ) 
		{
			if( iIndex == iSelIndex ) 
			{
				objSelectDay.options[iIndex] = new Option(iIndex,iIndex,false,true);
			} 
			else if (iIndex == iDays  && iIndex < iSelIndex)
			{		
				objSelectDay.options[iIndex] = new Option(iIndex,iIndex,false,true);
			} else {
				objSelectDay.options[iIndex] = new Option(iIndex,iIndex,false,false);
			}
		}
	}