Two analogies that relate items to whether they are trash or treasure is given in the form "A : B. C : ?". Items marked as "trash" are considered to not have value and can be disposed, whereas those marked as "treasure" are considered valuable items that must be retained. "A : "B relates item A to whether it is trash or treasure, as specified by B. Your task is to replace the question mark (?) with either `trash` or `treasure` for the given item C, following the "A : B" relation.

mold : trash. pillow : ?
treasure

dust : trash. mud : ?
trash

dust : trash. ring : ?

treasure