function show(start, end){ 


  var pic_start = document.getElementById("prod-" + start).src;
  var pic_last = document.getElementById("prod-" + end).src;

  document.getElementById("prod-" + start)
    alert(pic_start);
    alert(pic_last);


}

function swap(thispic){

  var pic_1 = document.getElementById("a").src;
  var pic_2 = document.getElementById(thispic).src;

  document.getElementById("a").src = pic_2.replace('_s.jpg','.jpg');
  document.getElementById(thispic).src = pic_1.replace('.jpg','_s.jpg');

}

function popup(id) {
	w = 800;
	h = 800;
	sw = screen.width - 250;
	sh = screen.height - 250;
	l = (sw - w) / 2;
	t = (sh - h) / 2;
	window.open("popup.php?id=" + id, '_blank', 'width='+w+',height='+h+',top='+t+',left='+l+',scrollbars=yes,resizable=yes');	
}