خر در چمن فراوونه!!

main.py

number = (input()).split(" ")

a = int(number[0])
b = int(number[1])
l = int(number[2])

sums = 0

for i in range(1, l + 1):
    if i % 2 != 0:
        sums += a
    else:
        sums += b

print(sums)