In his grandfather's notebook Nicola found a description of an old game called "Bulls and Cows", which was popular amongst ancient humans. He wants to try and play it with Stephan, but Nicola does not losing games. That's where we come in!
The host thinks up a 4-digits sequence. The digits must all be different. Then, in turn, you try to guess the sequence. If the matching digits are on their right positions, they are called "bulls", when they are on different positions, they are "cows". The host tells you how many "bulls" and "cows" you've guessed. You should attempt to solve the code in eight turns (it is however, possible in seven turns).
On each step,..., where: