Bulls and Cows is a 2 player game. One player thinks of a number, while the other player tries to guess it. • The number to be guessed must be a 4 digit number, using only digits from 1 - 9, each digit atmost once. e.g. 1234 is valid, 0123 is not valid, 9877 is not valid, 9876 is valid. • For every guess that the player makes, he gets 2 values - the number of bulls and the number of cows. 1 bull means the guess contains and the target number have 1 digit in common, and in the correct position. 1 cow means the guess and the target have 1 digit in common, but not in correct position. e.g. Let the target be 1234. Guessing 4321 will give 0 bulls and 4 cows. 3241 will give 1 bull and 3 cows. 4 bulls means you have won the game! • The player gets 7 chances to correctly guess the entire number.

https://en.wikipedia.org/wiki/Bulls_and_Cows