Convert Decimal number to Roman and vice versa

decimalRoman.py

def decToRoman(n):
	dec = {
		"1": "I",
		"5": "V",
		"10": "X",
		"50": "L",
		"100": "C",
		"500": "D",
		"1000": "M"
	}
	m = 1000
	roman = ""
	while n > 0 and m > 0:
		x = n // m
		c = dec[str(m)]
		if x > 8:
			roman = roman + c + dec[str(m * 10)]
		elif x >= 5:
			roman = roman + dec[str(m * 5)] + "".join([c * (x - 5)])
		elif x > 3:
			roman = roman + c + dec[str(m * 5)]
		elif n >= m:
			roman = roman + "".join([c * x])
		n = n - m * x
		m = m // 10
	return roman

def romanToDec(s):
	rom = {
		"I": 1,
		"V": 5,
		"X": 10,
		"L": 50,
		"C": 100,
		"D": 500,
		"M": 1000
	}
	dec = psum = 0
	p = ''
	for c in s:
		if c == p:
			psum = psum + rom[c]
		elif psum > rom[c]:
			dec = dec + psum
			psum = rom[c]
		elif psum < rom[c]:
			psum = rom[c] - psum
		p = c
	return dec + psum