function show(box_id) {
  document.getElementById('g_nr'+box_id).style.display = "block";
  document.getElementById('k_nr'+box_id).style.display = "none";

  for (var i=1; i<=3; i++) {
      if (i != box_id) {
        document.getElementById('k_nr'+i).style.display = "block";
		document.getElementById('g_nr'+i).style.display = "none";
      }
  }
}