A Megamind was captured and brought to an island where a 1000 natives live. Some natives always tell the truth and some always lie. There is at least one truth teller on the island. The Megamind was promised to be kept alive if he can point out the liars from the truth-tellers. Every hour, the Megamind is allowed to call up a number of natives and ask a single question: "How many of you are truth-tellers?" or "How many of you are the liars?" How many hours does the Megamind need before he can determine the liars/truth-tellers?