def test3(self):
lst = ['b', 'bc', 'ac', 'adc']
res = longest_chain(lst)
self.assertEqual(res, 2)
res2 = longest_chain2(lst)
self.assertEqual(res2, 2)
print res
def test1(self):
lst = ['a','a', 'b', 'ba', 'bca', 'bda', 'bdca']
res = longest_chain(lst)
self.assertEqual(res, 4)
print res
