var n = 7;


var f = false;


var b = new Array;


var c;


function prel(){





   	if(document.images) {


	  for(i=1;i<=n;i++)


               {str = 'Images/p' + i + '_o.gif';


               b[i-1] = new Image();


               b[i-1].src = str;


}


		c = new Image();


		c.src = 'Images/arrow.gif'


            	f = true;


 		}


}


function on(im){


	if (document.images && (f == true)) 


		{


		 document.images[im].src = "Images/"+im+"_o.gif";}


		


}


function off(im){


	if (document.images && (f == true))


		document.images[im].src = "Images/"+im+".gif";


}





function l_on(im){


	if (document.images && (f == true)) 


		


		 document.images[im].src = "Images/arrow.gif";


	


}


function l_off(im){


	if (document.images && (f == true))


		document.images[im].src = "Images/spacer.gif";


}