Problem: Fishland

mussels = 7.50
mackerel = float(input())
sprats = float(input())
kg_tuna = float(input())
kg_scads = float(input())
kg_mussels = int(input())
tuna_price = mackerel + (mackerel * 0.60)
sum_tuna = kg_tuna * tuna_price
scads_price = sprats + (sprats * 0.80)
sum_scads = kg_scads * scads_price
sum_mussels = kg_mussels * mussels
bill = sum_tuna + sum_scads + mussels
print(f'{bill:.2f}')