initial_slime = 0
generations_of_propogation = 0
starting_slime_value = 0


def ask_for_initial_amount():
    global initial_slime
    initial_slime = float(input("Initial slime amount (grams)-"))


ask_for_initial_amount()


def ask_for_generations_of_propogation():
    global generations_of_propogation
    generations_of_propogation = int(input("Generations of propogation---"))


ask_for_generations_of_propogation()

while initial_slime < 0:
    print("Error")
    ask_for_initial_amount()

while generations_of_propogation <= 0:
    print("Error: value must be a positive integer")
    ask_for_generations_of_propogation()

slime_amount = initial_slime

if generations_of_propogation > 0:
    for number in range(0, generations_of_propogation):
        total_slime = starting_slime_value + slime_amount
        starting_slime_value = slime_amount
        slime_amount = total_slime
elif generations_of_propogation == 1:
    total_slime = initial_slime

print("")
print("Final slime amount (grams)--- %7.3f" % slime_amount)