$(document).ready(function(){
			$("ul.main_menu li").mouseenter(function(){
	        if (!$(this).children(".main_drop_menu").length) {
	            return;
	        }
	        if (!$(this).children(".main_drop_menu").is(':visible')) {
	            $('.main_menu_a').removeClass('main_menu_a');
	            $(".main_drop_menu").hide();
	            $(this).children(".main_drop_menu").show();
	        }
	        $(this).addClass('main_menu_a');
            });
			$("ul.main_menu li").mouseleave(function(){
	        if (!$(this).children(".main_drop_menu").length) {
	            return;
	        }
	        if (!$children(".main_drop_menu").is(':visible')) {
	            $('.main_menu_a').removeClass('main_menu_a');
	            $(".main_drop_menu").hide();
	            $(this).children(".main_drop_menu").show();
	        }
	        $(this).addClass('main_menu_a');
	        });
	    $(".main_drop_menu").mouseleave(function(){
	        $('.main_menu_a').removeClass('main_menu_a');

	        $(".main_drop_menu").hide();
	    });
	});