class SLLNode<E> {
	protected E element;
	protected SLLNode<E> succ;

	public SLLNode(E elem, SLLNode<E> succ) {
		this.element = elem;
		this.succ = succ;
	}

	@Override
	public String toString() {
		return element.toString();
	}
}

class SLL<E> {
	private SLLNode<E> first;

	public SLL() {
		// Construct an empty SLL
		this.first = null;
	}

	public void deleteList() {
		first = null;
	}

	public int length() {
		int ret;
		if (first != null) {
			SLLNode<E> tmp = first;
			ret = 1;
			while (tmp.succ != null) {
				tmp = tmp.succ;
				ret++;
			}
			return ret;
		} else
			return 0;

	}

	@Override
	public String toString() {
		String ret = new String();
		if (first != null) {
			SLLNode<E> tmp = first;
			ret += tmp + "->";
			while (tmp.succ != null) {
				tmp = tmp.succ;
				ret += tmp + "->";
			}
		} else
			ret = "Prazna lista!!!";
		return ret;
	}

	public void insertFirst(E o) {
		SLLNode<E> ins = new SLLNode<E>(o, first);
		first = ins;
	}

	public void insertAfter(E o, SLLNode<E> node) {
		if (node != null) {
			SLLNode<E> ins = new SLLNode<E>(o, node.succ);
			node.succ = ins;
		} else {
			System.out.println("Dadenot jazol e null");
		}
	}

	public void insertBefore(E o, SLLNode<E> before) {

		if (first != null) {
			SLLNode<E> tmp = first;
			if(first==before){
				this.insertFirst(o);
				return;
			}
			//ako first!=before
			while (tmp.succ != before)
				tmp = tmp.succ;
			if (tmp.succ == before) {
				SLLNode<E> ins = new SLLNode<E>(o, before);
				tmp.succ = ins;
			} else {
				System.out.println("Elementot ne postoi vo listata");
			}
		} else {
			System.out.println("Listata e prazna");
		}
	}

	public void insertLast(E o) {
		if (first != null) {
			SLLNode<E> tmp = first;
			while (tmp.succ != null)
				tmp = tmp.succ;
			SLLNode<E> ins = new SLLNode<E>(o, null);
			tmp.succ = ins;
		} else {
			insertFirst(o);
		}
	}

	public E deleteFirst() {
		if (first != null) {
			SLLNode<E> tmp = first;
			first = first.succ;
			return tmp.element;
		} else {
			System.out.println("Listata e prazna");
			return null;
		}
	}

	public E delete(SLLNode<E> node) {
		if (first != null) {
			SLLNode<E> tmp = first;
			if(first ==node){
				return this.deleteFirst();
			}
			while (tmp.succ != node && tmp.succ.succ != null)
				tmp = tmp.succ;
			if (tmp.succ == node) {
				tmp.succ = tmp.succ.succ;
				return node.element;
			} else {
				System.out.println("Elementot ne postoi vo listata");
				return null;
			}
		} else {
			System.out.println("Listata e prazna");
			return null;
		}

	}

	public SLLNode<E> getFirst() {
		return first;
	}

	public SLLNode<E> find(E o) {
		if (first != null) {
			SLLNode<E> tmp = first;
			while (tmp.element != o && tmp.succ != null)
				tmp = tmp.succ;
			if (tmp.element == o) {
				return tmp;
			} else {
				System.out.println("Elementot ne postoi vo listata");
			}
		} else {
			System.out.println("Listata e prazna");
		}
		return first;
	}
}

public class HelloWorld {
    public static void changeList(SLL<Integer> list, int n){
        SLLNode<Integer> current = list.getFirst();
        SLLNode<Integer> next = null;
        while(current != null){
            if(current.element % 2 == 0){
                next = current.succ;
                while(next != null && !(next.element % 2 == 0)){
                    next = next.succ;
                }
                if(next == null)
                    break;
                int sum = current.element - next.element;
                list.insertBefore(sum, current);
                list.delete(current);
                list.delete(next);
            }else {
                next = current.succ;
                while(next != null && next.element % 2 == 0){
                next = next.succ;
            }
                if(next == null)
                    break;
                int sum = current.element + next.element;
                list.insertBefore(sum, current);
                list.delete(current);
                list.delete(next);
            }
            current = current.succ;
        }
        System.out.println(list);
    }

    public static void main(String args[]) {
        SLL<Integer> list = new SLL<Integer>();
        int n = 8;
            list.insertLast(1);
              list.insertLast(2);
                list.insertLast(3);
                  list.insertLast(4);
                    list.insertLast(5);
                      list.insertLast(6);
                        list.insertLast(7);
                          list.insertLast(8);

        changeList(list, n);
    }
}