print "se imprimen los ... usando and "
for a in range(20):
  if (a%2 == 0) and (a%3 == 0):
     print a
print "fin del programa "

print "se imprimen los ... sin usar and "
for a in range(20):
  if (a%2 == 0): 
    if (a%3 == 0):
      print a
print "fin del programa "