value=1;
function show(pict_nr) {
  document.stad.src = pict[pict_nr];
document.getElementById("source").innerHTML='<br>'+text[pict_nr]+'<br><br>Picture <font color=red>'+pict_nr+'</font> of <font color=red>'+images+'</font>';    
  value = pict_nr;
}
function RND() {
  value = Math.floor(Math.random()*images);
  show(value);
}
function forward() {
  value--;
  if(value<1) value = images ;
  show(value);
}
function next() {  
  value++;
  if (value>images) value = 1;
  show(value);
}