// JavaScript Document

function ChangeDays(suffix)
{
  day = document.getElementById("day"+suffix).selectedIndex;

  days = document.getElementById("day"+suffix).length;
	
  days = GetDays(suffix);

  while(document.getElementById("day"+suffix).options.length > 28) 
  {
    document.getElementById("day"+suffix).options[28] = null;
  }
  
  for (var i = 28; i < days; i++)
  {
    document.getElementById("day"+suffix).options[i] = new Option(i+1, i+1);
  }

  if(day > days - 1)
  {
    day = days - 1;
  }
  
  document.getElementById("day"+suffix).options[day].selected = true;
}

function GetDays(suffix)
{
  mon = document.getElementById("month"+suffix).selectedIndex + 1;
  yr = document.getElementById("year"+suffix).options[document.getElementById("year"+suffix).selectedIndex].value;

  return GetDaysEx(mon, yr);
}

function GetDaysEx(mon, yr)
{
  if(mon == 1 || mon == 3 || mon == 5 || mon == 7 || mon == 8 || mon == 10 || mon == 12)
    return 31;
  if(mon == 4 || mon == 6 || mon == 9 || mon == 11)
    return 30;
  if(mon == 2 && yr % 400 == 0)
    return 29;
  if(mon == 2 && yr % 100 == 0)
    return 28;
  if(mon == 2 && yr % 4 == 0)
    return 29;
  if(mon == 2)
    return 28;

  return 0;
}