def main():
    #lines = [12, 14, 1969, 100756]
    with open("01ain.txt", "r") as file:
        lines = file.readlines()
    masses = [int(x) for x in lines]
    fuels = [(x//3) - 2 for x in masses]
    newfuels = []
    for fuel in fuels:
        of = fuel
        f = fuel
        while f > 0:
            af = (f//3) - 2
            if af > 0:
                of += af
                f = af
            else:
                f = 0
        newfuels.append(of)
    #print(newfuels)
    print(sum(newfuels))

if __name__ == "__main__":
    main()