Roman Numeral and Int Conversion

romnum.py

#!/usr/bin/python3

import roman

errmsg = '\nOnly whole numbers or Roman Numerals between 1 and 3999 excepted\n'
number = input('Enter a number between 1 and 3999 in either Integer or Roman Numeral format> ')
if number.isalpha():
    try:
        print(roman.fromRoman(number.upper()))
    except roman.InvalidRomanNumeralError:
        print(errmsg)
else:
    try:
        number = int(number)
        if number == 0 or number > 3999:
            exit(0)
    except:
        print(errmsg)
        exit(0)
    try:
        print(roman.toRoman(number))
    except roman.OutOfRangeError:
        print(errmsg)
    except roman.NotIntegerError:
        print(errmsg)