void remove(E elem) {
        System.out.println("Remove: ");
        if(root == null) return;
        if(elem == null) return;
        if(!contains(elem)){
            return;
        }
        Node<E> parent = null;
        Node<E> z = root;

        while(!(elem.equal(z.contents))){
            parent = z;
            if(elem.lessOrEqual(z.contents)){
                z = z.left;
            }else{
                z = z.right;
            }
        }

        if(z.left == null && z.right == null){                  //uzel nema potomky
            if(parent == null){
                root = null;
                return;
            }

            if(parent.left!=null){
                    if(parent.left.equals(z)){
                        parent.left = null;
                        return;
                    }
                }
                if(parent.right!=null){
                    if(parent.right.equals(z)){
                        parent.right = null;
                        return;
                    }
                }

        }

        if((z.left!= null && z.right == null)||(z.left == null && z.right != null)){    //uzel ma jen jednoho potomka
            if(z.right == null){
                z.left.setParent(parent);
                if(parent == null){
                    z.left = root;
                    return;
                }
                if(parent.left!=null){
                    if(parent.left.equals(z)){
                        parent.left = z.left;
                        return;
                    }
                }
                if(parent.right!=null){
                    if(parent.right.equals(z)){
                        parent.right = z.left;
                        return;
                    }
                }

            }else{
                z.right.setParent(parent);
                if(parent == null){
                    z.right = root;
                    return;
                }
                if(parent.left!=null){
                    if(parent.left.equals(z)){
                        parent.left = z.right;
                        return;
                    }
                }
                if(parent.right!=null){
                    if(parent.right.equals(z)){
                        parent.right = z.right;
                        return;
                    }
                }

            }
        }



        if(z.left != null && z.right != null){  //mazany uzel ma oba potomky
            Node<E> maxPar = z;
            //Node<E> help4 = z;
            Node<E> max;
            max = z.left;
            while(max.right != null){
                max = max.right;
            }
            if(z.left.equals(max)){             //maximum leveho podstromu z je hned z.left
                max.right = z.right;
                z.right.setParent(max);
                max.setParent(parent);
                if(parent == null){
                    root = max;
                    return;
                }
                if(parent.left!=null){
                    if(parent.left.equals(z)){
                        parent.left = max;
                        return;
                    }
                }
                if(parent.right!=null){
                    if(parent.right.equals(z)){
                        parent.right = max;
                        return;
                    }
                }
                return;
            }else{                                          //maximum leveho podstromu je az nekde na z.left.right..right
                maxPar = maxPar.left;
                while(maxPar.right.right != null){
                    maxPar = maxPar.right;
                }
                z.left.setParent(max);
                z.right.setParent(max);
                max.setParent(parent);
                if(max.left != null){
                    max.left.setParent(maxPar);
                }
                maxPar.right = max.left;
                max.left = z.left;
                max.right = z.right;
                if(parent == null){
                    root = max;
                    return;
                }
                if(parent.left!=null){
                    if(parent.left.equals(z)){
                        parent.left = max;
                        return;
                    }
                }
                if(parent.right!=null){
                    if(parent.right.equals(z)){
                        parent.right = max;
                        return;
                    }
                }
            }

        }

    }