function showhide(id){
    var obj = document.getElementById("sub").children;
	for (var i = 0; i < obj.length; i++) { 
		obj[i].style.display = 'none';
    }

    var obj = document.getElementById("topmenu").children;
	for (var i = 0; i < obj.length; i++) { 
		obj[i].className = '';
    }

	var subject = document.getElementById("ul"+id);
    subject.style.display = subject.style.display!='block' ? 'block' : 'none';

	var subject = document.getElementById("li"+id);
    subject.className = 'act';
}