Conversion of Roman numbers 2

Our numbers 1, 2, 3, 4 ... are called Arabic, and numbers written with letters are called Roman numbers.

1. Roman numerals are written using the letters:
   1. I =1
   2. V =5
   3. X =10
   4. L =50
   5. C =100
   6. D =500
   7. M =1 000
2. Roman numerals consist of the letters from the highest to the lowest. At most 3 same Roman numerals (XXX = 30, III = 3) are combined.
3. The smaller Roman numeral before the larger indicates the subtraction (IV = 4, 5 - 1 = 4, V - I = IV). Only one Roman numeral is subtracted in this way.
4. Subtraction according to the above rule applies to Roman numerals I, X, C.
5. The numeral I is used for subtraction only before V and X.

Convert the Roman number to "our" number.