public void push(int item)
        {
            StackWithBottom <int> lastStack = getLastStack();

            if (lastStack != null && !lastStack.isFull())
            {
                lastStack.push(item);
            }
            else
            {
                StackWithBottom <int> stack = new StackWithBottom <int>(capacity);
                stack.push(item);
                list.Add(stack);
            }
        }