def test_1926(self): self.assertEqual("19:26", max_valid_time(1, 2, 6, 9))
def test_1832(self): self.assertEqual("23:18", max_valid_time(1, 8, 3, 2))
def test_0909(self): self.assertEqual("09:09", max_valid_time(0, 9, 9, 0))
def test_0940(self): self.assertEqual("09:40", max_valid_time(0, 9, 4, 0))
def test_6985(self): self.assertEqual("NOT POSSIBLE", max_valid_time(6, 9, 8, 5))
def test_9945(self): self.assertEqual("NOT POSSIBLE", max_valid_time(9, 9, 4, 5))
def test_1945(self): self.assertEqual("19:54", max_valid_time(1, 9, 4, 5))