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coin - n. a small, flat, and usually round piece of metal issued by a government as money
seal - n. an official mark that is stamped on paper or on a small piece of wax to show that something (such as a document) is genuine and has been officially approved
challenge - n. a difficult task or problem : something that is hard to do
certainly - adv. without doubt
appropriate - adj. right or suited for some purpose or situation
gross - adj. rude or offensive
input - n. advice or opinions that help someone make a decision
