def reverse_roman(roman_string):
    d =    [['M',1000], ['CM',900],
            ['D',500],  ['CD',400],
            ['C',100],  ['XC',90],
            ['L',50],   ['XL',40],
            ['X',10],   ['IX',9],
            ['V',5],    ['IV',4],
            ['I',1]]
    summ = 0
    for i in d:
        while (roman_string[:len(i[0])] == i[0]):
            summ+=i[1]
            roman_string = roman_string[len(i[0]):]
    return summ