$(document).ready(function(){
  
    lastBlock = $("#a1");
	firstBlock=$("#a2")
    maxWidth = 665;
    minWidth = 23;	

    $("ul li span").click(
      function(){
        $(lastBlock).animate({width: minWidth+"px"}, { queue:false, duration:400 });
		$(this).animate({width: maxWidth+"px"}, { queue:false, duration:400});
		$(lastBlock).removeClass('endOne');
		$(lastBlock).addClass('lastOne');	
		lastBlock = this;
	   
	   });
	   
	   $("ul li span.lastOne").click(function(){
			$(this).addClass('endOne');	   
	   });
	   
});