function showPic(picID){

for(i=1; i<5; i++) {
	pictureID = 'pic' + i;
	var d=document.getElementById(pictureID);
	
	if (picID == pictureID)
		d.style.display="block";
	else
		d.style.display="none";
}
}

function showLayer(layerID){
	var d=document.getElementById(layerID);
	d.style.display="block";
}

function hideLayer(layerID){
	var d=document.getElementById(layerID);
	d.style.display="none";
}