Mastermind (Bulls & cows)

"Mastermind" (or "Bulls and Cows" or "Codebreaker")  is a logical game where you need to guess the secret code. 

The code is a sequence of colored chips, depending on the settings the secret code can contain 4, 5 or 6 chips. They can be repeated (no more than two chips of the same color for codes with 4 and 5 chips and no more than three chips in the same color for 6 chips codes.) 
 At each turn, a player tries to guess the color and sequence of chips in the code and receives several hints. The hints can be white (cow) or black (bull): 
The white hint means that the color of a chip is correct;
The black hint means that color and the position of some chip are guessed correctly. 
The order of the hints does not matter and does not depend on the order of the chips in the code.

This process continues until the player finds the secret code.

Once per day you can try to solve the daily code and compare your results with the results of other breakers.