Advent of Code 2019, Day 1 Part 2

import math

inputFile = open("modules.txt", "r")
outputFile = open("answer.txt", "w")

sum = 0

for i in inputFile:
    mass = int(i)
    fuel = (math.trunc(mass/3))-2
    fuelTotal = fuel
    while (fuel > 0):
        fuel = (math.trunc(fuel/3))-2
        if (fuel > 0):
            fuelTotal = fuelTotal + fuel
    sum = sum + fuelTotal

outputFile.write(str(sum))

inputFile.close()
outputFile.close()