function verstecke(){
         Bilder = new Array('pic0','pic1','pic2','pic3','pic4','pic5','pic6','pic7','pic8','pic9','pic10','pic11','pic12','pic13','pic14','pic15');
         for (var i = 0; i < Bilder.length; ++i){
           document.getElementById(Bilder[i]).style.display="none";
           }
         }

function zeige(index){
         verstecke();
         document.getElementById(index).style.display="block";
         }