Roman to arabic.py

import pdb

d = {"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}

while True:
    num = input("Input a Roman Numeral to convert it to Arabic numbers: ")
    if num.lower() == "quit" or num.lower() == "q":
        break
    total = 0
    x = 0
    while x < len(num)-1:
        pdb.set_trace()
        try:
            if d[num[x]] > d[num[x+1]]:
                total += d[num[x]]
            else:
                total += (d[num[x+1]] - d[num[x]])
                x += 1
        except KeyError:
            print("Error: invalid entry.")
            x = len(num)
        x += 1
    total += d[num[-1]]
    print(num + ": " + str(total))