$(document).ready(function() {
	$(".menu_item").find("img").hover(function() {
		this.src = "images/"+this.id+"b.png";
	}, function() {
		var start = 0;
		if(this.src.substr(this.src.length-5) == 'b.png') {
			start = 5;
		} else {
			start = 4;
		}
		var img_name = this.src.substr(0, this.src.length-start);
		this.src = "images/"+this.id+".png";
	});
});