Statement

Giorgio is developing a new online FPS game! As he should now have got rid of most bugs, he decided to start a beta program. The game is now released free to play, with a disclaimer kindly asking each user to play only a single game (except of course for Giorgio's user, which can play as many games as he likes). Since the game is still in the development phase, it is currently run on a very small server, which is having trouble handling the traffic resulting from the beta release. Giorgio is thus starting to wonder whether some users are playing multiple games, ignoring his polite request! You are given the server logs, which consist of the N user identifiers V_i (0 < i < N) of the games played so far. Among them are included the games played by Giorgio himself; however, the identifiers are anonymised so that you are unable to distinguish his one from the others. Help Giorgio check whether there are users playing multiple games!