List
For a dynamic list L of integers, perform a sequence of the following operations.
L has a special element called END at the end of the list and an element of L is indicated by a cursor.
insert(x): Insert x before the element indicated by the cursor. After this operation, the cursor points the inserted element.
move(d): Move the cursor to the end by d, if d is positive. Move the cursor to the front by d, if d is negative.
erase(): Delete the element indicated by the cursor. After this operation, the cursor points the element next to the deleted element.
In case there is no such element, the cursor should point END. In the initial state, L is empty and the cursor points END.