public void add(Integer e){
    if(last == null){
       last = new Element(e,null);
       first = last;
    }else{
       Element tmp = last;
       last = new Element(e,null);
       tmp.setLink(last);
       if(first.getLink() == null)
        first.setLink(last);
    }
   }

   public void add(int i, Integer e){
    int count =1;
    Element temp = first;
    Element temp2;
    Element temp3 = first;

    if(last == null || first.getLink() ==null)
       add(e);

    else {
       while (count!=i){
          temp = temp.next();
          count++;
       }
       first = new Element (e,temp);
       temp.setLink(temp.next());

       while(temp3.hasNext()){
          temp3 = temp3.next();
       }
       last = temp3;
    }

   }