var x=0;
      var speed=50; 
      var move=10; 
      var loop,obj,max;
      initScroll();

      function scrollDown(){
        if(x-move>=-max){x-=move}else{loop=false;}
        obj.style.top = x
        if(loop)setTimeout(scrollDown,speed); 
      }

      function scrollUp(){
        if(x+move<=0){x+=move}else{loop=false;}
        obj.style.top = x
        if(loop)setTimeout(scrollUp,speed);
      }  
      
      function initScroll(){
        obj=document.getElementById("n3c"); 
        max=obj.offsetHeight-obj.parentNode.offsetHeight+5;
        if(max<=0)document.getElementById("arrows").style.display="none";    
      }