Two analogies that signify affordances are given in the form "A : B. C : ?". Affordance is the possibility of an action being done on an object, for example book is an affordance of writing. The phrase "A : B" implies that B is an affordance of A. Your task is to replace the question mark (?) with the appropriate affordance of the given action C, following the "A : B" relation. Your answer should be a single object without further explanation.

Ex Input:
operate : machine. cure : ?

Ex Output:
disease


Ex Input:
heal : wound. give : ?

Ex Output:
gift


Ex Input:
sing : song. write : ?

Ex Output:

letter