Minor technical fixes.
"Bulls and cows" is a logic game in which one of the players should guess what number the other player chosen in a few attempts.
In our game we are going to guess a four-digit number. The digits in this number should not be repeated.
The first player calls a guess, any four-digit number. If there are digits that stand on the same positions as in the hidden number, these are bulls. If the numbers are the same, but they are in different positions, they are cows.
Try to guess a four-digit number faster, than Android.
