var picNum = 0;
var nn;
var flag=0;

function initFocus(i) {
	picNum = i;
	nn=1;
	setTimeout('change_img()',3000);
}

function change_img(){
	var num = picNum-1;
	num = num+1; 
	if(flag==1)  num=num-1;
	if(num>picNum) num = picNum;
	if(nn>num) nn=1;
	setTimeout('setFocus('+nn+')',3000);
	nn++;
	tt=setTimeout('change_img()',3000);
}

function setFocus(i){
	selectLayer(i);
}

function selectLayer(i){
 	for(var id = 1;id<=picNum;id++){
  		if(id==i)
  			document.getElementById("focusPic"+id).style.display="block";
  		else
  			document.getElementById("focusPic"+id).style.display="none";
 	}  
}