function timer()
{
  now= new Date();

  seichas=now.getMinutes();

  if(seichas>30)
  {
    minute=89-now.getMinutes();
  }
  else
  {
    minute=59-now.getMinutes();
  }

  second=59-now.getSeconds();

  if(minute<10)
  {
    minute="0" + minute;
  }
  if(second<10)
  {
    second="0" + second;
  }

  document.getElementById("timer").innerHTML=("00:" + minute + ":" + second);
  setTimeout("timer()",1000);
}