# Arup Guha
# 9/27/24
# Solution to 2024 UCF Qualifier Problem: Farmers' Market

toks = input().split()
nApples = int(toks[0])
nBags = int(toks[1])
price = int(input().strip())

# Calculate dozens via ceiling of division by 12.
dozens = (nApples * nBags + 11)//12

# Ta da!
print(price*dozens)