document.onkeydown = move_page
    function move_page(e) {
	var keycode;
	if (window.event) keycode = window.event.keyCode;
	else if (e) keycode = e.which;
	//alert("keycode: " + keycode);
	if (keycode == 37 && page_no > 0)
	 window.location = ''+(page_no-1)+'.html';
	if (keycode == 39 && page_no < pages_size - 1 )
	 window.location = ''+(page_no+1)+'.html';
    }