Let c_c and p_c denote the prices today of a compound call and a compound put with the same expiration date T, same strike price K, and same underlying call. Let c denote today's price of the underlying call. Formulate the put-call relation between c_c and p_c. Note that you do not need to know the strike price K' and expiration date T' > T of the underlying call, just its price today c