For those who are unfamiliar with Roman Numerals, here is a quick summary: Each letter used in Roman numerals stands for a different number: Roman Numeral Number -------------------------- I 1 V 5 X 10 L 50 C 100 D 500 M 1000A string of letters means that their values should be added together. For example, XXX = 10 + 10 + 10 = 30, and LXI = 50 + 10 + 1 = 61. If a smaller value is placed before a larger one, we subtract instead of adding. For instance, IV = 5 − 1 = 4 and XC = 100 − 10 = 90. Except for M, do not add more than three of the same letters together. Subtract only powers of ten, such as I, X, or C. Writing VL for 45 is not allowed: write XLV instead. Subtract only a single letter from a single numeral. Write VIII for 8, not IIX; 19 is XIX, not IXX. Don't subtract a letter from another letter more than ten times greater. This means that you can only subtract I from V or X, and X from L or C, so MIM is illegal.

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