var yy;
yy=2;
setTimeout('change_img()',2000);  
function change_img()  
{  
 if(yy>4) yy=1; 
 setTimeout('setFocus1('+yy+')',4000);  
 yy++;  
setTimeout('change_img()',4000);  
}  
function setFocus1(i)  
{  
 selectLayer1(i);  
}  
function selectLayer1(i)  
{  
 switch(i)  
 {  
 case 1:  
 document.getElementById("focusPic1").style.display="block";  
 document.getElementById("focusPic2").style.display="none";  
 document.getElementById("focusPic3").style.display="none";  
 document.getElementById("focusPic4").style.display="none";  
 break;  
 case 2:  
 document.getElementById("focusPic1").style.display="none";  
 document.getElementById("focusPic2").style.display="block";  
 document.getElementById("focusPic3").style.display="none";  
 document.getElementById("focusPic4").style.display="none";  
 break;  
 case 3:  
 document.getElementById("focusPic1").style.display="none";  
 document.getElementById("focusPic2").style.display="none";  
 document.getElementById("focusPic3").style.display="block";  
 document.getElementById("focusPic4").style.display="none";   
 break;  
 case 4:  
 document.getElementById("focusPic1").style.display="none";  
 document.getElementById("focusPic2").style.display="none";  
 document.getElementById("focusPic3").style.display="none";  
 document.getElementById("focusPic4").style.display="block";   
 break;  
 }  
}