import unittest

I = 'I'
V = 'V'
X = 'X'
L = 'L'
C = 'C'
M = 'M'


def convert(number):
    if number <= 0:
        raise Exception()
    if number < 4:
        return I * number
    if number == 4:
        return I + V
    if 5 <= number <= 8:
        return V + I * (number - 5)
    if number == 9:
        return I + X
    if number >= 1000:
        remainder = number % 1000
        times = number / 1000
        try:
            _ = convert(remainder)
        except:
            _ = ''
        return 'M' * times + _
    elif number >= 900:
        try:
            _ = convert(number - 900)
        except:
            _ = ''
        return 'CM' + _
    elif number >= 500:
        try:
            _ = convert(number - 500)
        except:
            _ = ''
        return 'D' + _
    if number >= 100:
        remainder = number % 100
        times = number / 100
        try:
            _ = convert(remainder)
        except:
            _ = ''
        return 'C' * times + _
    elif number >= 90:
        try:
            _ = convert(number - 90)
        except:
            _ = ''
        return 'XC' + _
    elif number >= 50:
        try:
            _ = convert(number - 50)
        except:
            _ = ''
        return 'L' + _
    elif number >= 10:
        remainder = number % 10
        times = number / 10
        try:
            _ = convert(remainder)
        except:
            _ = ''
        return 'X' * times + _


class RomaTest(unittest.TestCase):
    def test_0_raise_error(self):
        with self.assertRaises(Exception):
            convert(0)

    def test_1_return_I(self):
        roma = convert(1)
        self.assertEqual(roma, I)

    def test_2_return_II(self):
        roma = convert(2)
        self.assertEqual(roma, I + I)

    def test_3_return_III(self):
        roma = convert(3)
        self.assertEqual(roma, I + I + I)

    def test_4_return_IV(self):
        roma = convert(4)
        self.assertEqual(roma, I + V)

    def test_5_return_V(self):
        roma = convert(5)
        self.assertEqual(roma, V)

    def test_6_return_VI(self):
        roma = convert(6)
        self.assertEqual(roma, 'VI')

    def test_9_return_IX(self):
        roma = convert(9)
        self.assertEqual(roma, I + X)

    def test_10_return_C(self):
        roma = convert(10)
        self.assertEqual(roma, X)

    def test_18_return_C(self):
        roma = convert(18)
        self.assertEqual(roma, 'XVIII')

    def test_19_return_XIX(self):
        roma = convert(19)
        self.assertEqual(roma, 'XIX')

    def test_20_return_XX(self):
        roma = convert(20)
        self.assertEqual(roma, 'XX')

    def test_50_return_L(self):
        roma = convert(50)
        self.assertEqual(roma, L)

    def test_66_return_LXVI(self):
        roma = convert(66)
        self.assertEqual(roma, 'LXVI')

    def test_88_return_LXXXVIII(self):
        roma = convert(88)
        self.assertEqual(roma, 'LXXXVIII')

    def test_90_return_XC(self):
        roma = convert(90)
        self.assertEqual(roma, 'XC')

    def test_99_return_XCIX(self):
        roma = convert(99)
        self.assertEqual(roma, 'XCIX')

    def test_101_return_CI(self):
        roma = convert(101)
        self.assertEqual(roma, 'CI')

    def test_500_return_D(self):
        roma = convert(500)
        self.assertEqual(roma, 'D')

    def test_990_return_CMXC(self):
        roma = convert(990)
        self.assertEqual(roma, 'CMXC')

    def test_minus_1_raise_error(self):
        with self.assertRaises(Exception):
            convert(-1)

    def test_1000_return_M(self):
        roma = convert(1000)
        self.assertEqual(roma, M)

    def test_1001_return_M(self):
        roma = convert(1001)
        self.assertEqual(roma, 'MI')


if __name__ == '__main__':
    unittest.main()