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 todays 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 K0 and expiration date T 0 > T of the underlying call, just its price today c.

Hint: this argument is more like the one for usual put-call parity than the one for digital put-call parity