a = set('abracadabra')
b = set('alacazam')
print(a)                                  # unique letters in a
print(a - b)                             # letters in a but not in b
print(a | b)                             # letters in a or b or both
print(a & b)                              # letters in both a and b
print(a ^ b)                              # letters in a or b but not both
