[[wp:Bulls and Cows|This]] is an old game played with pencil and paper that was later implemented on computer.

The task is for the program to create a four digit random number from the digits 1 to 9, without duplication.
The program should ask for guesses to this number, reject guesses that are malformed, then print the score for the guess.

The score is computed as:
# The player wins if the guess is the same as the randomly chosen number, and the program ends.
# A score of one '''bull''' is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number.
# A score of one '''cow''' is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position.

;Cf,
* [[Bulls and cows/Player]]
* [[Guess the number]]
* [[Guess the number/With Feedback]]
