def oneBits(n):
  i = 0
  s = set()
  while n > 0:
    if n % 2 == 1:
      s.add(i)
    n = n / 2
    i += 1
  return s

def powerSet(n):
  p = []
  for i in range(0, 2 ** n):
     p.append(oneBits(i))
  return p


p = powerSet(3)
# print all the elements
for s in p:
  print s

print ""
print "few examples"
print ""

# print the intersection between the last set in P and the one before.
print "intersection ", p[-1] , " with ", p[-2]
print p[-1] & p[-2]

# print the diff between
print "diff ", p[-1] , "-", p[-2]
print p[-1] - p[-2]

# print the union
print "union of", p[-1], " U ", p[-2]
print p[-1] | p[-2]