var openid=0;
function ChangeMenu(id){
  if(openid != 0){
    document.getElementById('button' + openid).className="menu";
    document.getElementById('menu' + openid).className="hidden";
  }
  document.getElementById("menu" + id).className="visible";
  document.getElementById("button" + id).className="menuhidden";
  openid = id;
}