function ShowFirst() {
     descr.style.visibility = "";
     screen1.style.visibility = "hidden";
     instract.style.visibility = "hidden";
     reviews.style.visibility = "hidden";


     descr.style.display = "block";
     screen1.style.display = "none";
     instract.style.display = "none";
     reviews.style.display = "none";

     videos.style.visibility = "hidden";
     videos.style.display = "none";
    }

    function ShowSecond() {
     descr.style.visibility = "hidden";
     screen1.style.visibility = "";
     instract.style.visibility = "hidden";
     reviews.style.visibility = "hidden";

     descr.style.display = "none";
     screen1.style.display = "block";
     instract.style.display = "none";
     reviews.style.display = "none";

     videos.style.visibility = "hidden";
     videos.style.display = "none";
    
    }

    function ShowThird() {
     descr.style.visibility = "hidden";
     screen1.style.visibility = "hidden";
     instract.style.visibility = "";
     reviews.style.visibility = "hidden";

     descr.style.display = "none";
     screen1.style.display = "none";
     instract.style.display = "block";
     reviews.style.display = "none";

     videos.style.visibility = "hidden";
     videos.style.display = "none";
    
    }


    function ShowFour() {
     descr.style.visibility = "hidden";
     screen1.style.visibility = "hidden";
     instract.style.visibility = "hidden";
     reviews.style.visibility = "";

     descr.style.display = "none";
     screen1.style.display = "none";
     instract.style.display = "none";
     reviews.style.display = "block";

     videos.style.visibility = "hidden";
     videos.style.display = "none";

    }


    
    function ShowFive() {
     descr.style.visibility = "hidden";
     screen1.style.visibility = "hidden";
     instract.style.visibility = "hidden";
     reviews.style.visibility = "hidden";

     descr.style.display = "none";
     screen1.style.display = "none";
     instract.style.display = "none";
     reviews.style.display = "none";

     videos.style.visibility = "";
     videos.style.display = "block";

    }


    function ShowPage(i) {
     if(i == 1) {
       ShowFirst();
     }
     return false;
    }