"""File:     to_roman5.9.py
   Purpose:  Convert a Roman numeral into a Hindu-Arabic numeral.  
             Print a message if the character entered by the
             user isn't a legal Roman numeral, and quit.  This version 
             accepts both lower case and upper case letters.

   Run:      python to_roman5.9.py

   Input:    A Roman numeral
   Output:   Corresponding Hindu-Arabic numeral or error message
"""

from sys import exit

#----------------------------------------------------------------------
def convert_to_number(roman_sym):
   """Convert a single character Roman numeral into a number
   """
   if roman_sym == 'M' or roman_sym == 'm':
      return 1000
   elif roman_sym == 'D' or roman_sym == 'd':
      return 500
   elif roman_sym == 'C' or roman_sym == 'c':
      return 100
   elif roman_sym == 'L' or roman_sym == 'l':
      return 50
   elif roman_sym == 'X' or roman_sym == 'x':
      return 10
   elif roman_sym == 'V' or roman_sym == 'x':
      return 5
   elif roman_sym == 'I' or roman_sym == 'i':
      return 1
   else: 
      return None

#----------------------------------------------------------------------
# Program starts here
roman = raw_input("Enter a Roman numeral\n")
print "You entered", roman

number = 0
val = convert_to_number(roman[0])
for i in range(1,len(roman)):
   new_val = convert_to_number(roman[i])
   if val < new_val:
      number = number-val
   else:
      number = number+val
   val = new_val
number = number+val

print "The Roman numeral", roman, "corresponds to the"
print "    Hindu-Arabic numeral", number