ULTA's current stock price is $280. Its return volatility is 80%. Assume no dividend and a continuously compounding interest rate of 6%. Construct a two-step binomial tree with each step being 6-month based on the approach on the lecture notes, and value a 1-year $200-strike ULTA put option on this tree (You will be asked about the option's payoff, value, delta, and the tree probability in separate numerical questions on ULTA. So please keep the tree result to avoid repetition). What's the risk-neutral probability of going up at each branch of the tree? (round answer to 0.01)