var cq = 1;           
  var fq = 19;           
  var sd = 1;           
  var ep = 0;           
           
function nq(val) {           
   cq = val + 1;           
   if (cq > fq) { cq = fq; }  
   hideit(cq - 1);
   showit(cq);       
   if (cq == fq) {           
       var itm = document.getElementById('control-buttons');           
       itm.style.display="none";           
   }           

}
           
function showit(cq) {           
   var itm = document.getElementById("ss-" + cq);           
   itm.style.display="block";           
}           
           
function hideit(cq) {           
   var itm = document.getElementById("ss-" + cq);           
   itm.style.display="none";           
}