Current price of a non-dividend paying stock is $50. Use a two-step tree to value an AMERICAN PUToption on the stock with a strike price of $52 that expires in 6 months. Each step is 3 months and in each step the stock price either moves up by 10% or moves down by 10%. Suppose that the risk-free rate is 7% per annum continuous compounding. What should be this American put option price?