Implement the MasterMind game.

The computer "thinks" a number with 4 different digits. You guess which digits. For every digit that matched both in value, and in location the computer gives you a *. For every digit that matches in value, but not in space the computer gives you a +. Try to guess the given number in as few guesses as possible.

Computer: 2153 You: 2467 * You: 2715 *++