Symbolizing and proving an argument.

Symbolize and prove argument below:

If there is even one objectively valid moral principle(P), then Objectivism is true (O).  Further, if it is morally wrong to torture innocent persons for the fun of it (T), then there is at least one objectively valid moral principle.  Certainly it is wrong to torture innocent persons for the fun of it and really, the thought of such a thing is really disgusting (D).  Therefore Objectivism is true.