A stock price is currently 830. During each two-month period for the next four months it will increase by 8% or decrease by 10%. The risk-free interest rate is 5%. Use a two-step tree to calculate the value of a derivative that pays off [max(30 - S T , 0)1 2 , where ST is the stock price in four months. If the derivative is American style, should it be exercised early?