function Change_image() {
menu = document.getElementById('liste_pdf');
	i = menu.selectedIndex;
	if (i == 0) return;
	val = menu.options[i].value;
var img = document.getElementById('image_pdf');
 img.src =val.substring(0,val.lastIndexOf("+"));
    val2=val.substring(val.lastIndexOf("+"));
    document.getElementById('lien_pdf').href=val2.substring(1);

}