A stock price is currently $$\$ 30$$. During each 2-month period for the next 4 months it will increase by $8 \%$ or reduce by $10 \%$. The risk-free interest rate is $5 \%$. Use a two-step tree to calculate the value of a derivative that pays off $\left[\max \left(30-S_T, 0\right)\right]^2$, where $S_T$ is the stock price in 4 months. If the derivative is American-style, should it be exercised early?