this is too easy, next time give us less guesses or more numbers
we already got 2 numbers on the second try
You got two numbers half-right, and you still need to figure out where they belong. By guess 15, you should have either X or / /. By guess 10, you should have / / / /, X X, or X / /. By guess 5, you should have X X X or X X / /, and you need to have X X X X by the last guess.
EDIT: What if I increase the code length after every round?