function first()
      {
        document.getElementById("table1").style.display = "block";
        document.getElementById("table2").style.display = "none";
        document.getElementById("predesle").style.display = "none";
        document.getElementById("dalsi").style.display = "inline";
      }
  function second()
      {
        document.getElementById("table1").style.display = "none";
        document.getElementById("table2").style.display = "block";
        document.getElementById("predesle").style.display = "inline";
        document.getElementById("dalsi").style.display = "none";
      }