```
class Solution(object):
def getHint(self, secret, guess):
secret_numbers = [0] * 10
guess_numbers = [0] * 10
cows = 0
bulls = 0
for i in range(len(secret)):
if secret[i] == guess[i]:
bulls += 1
else:
if guess_numbers[int(secret[i])] > 0:
guess_numbers[int(secret[i])] -= 1
cows += 1
else:
secret_numbers[int(secret[i])] += 1
if secret_numbers[int(guess[i])] > 0:
secret_numbers[int(guess[i])] -= 1
cows += 1
else:
guess_numbers[int(guess[i])] += 1
return "{}A{}B".format(bulls, cows)
```