Fishland

cenaSkumriq = float(input())
cenaCaca = float(input())
kgPalamud = float(input())
kgSafrid = float(input())
kgMidi = int(input())

cenaPalamud = cenaSkumriq + cenaSkumriq * 0.60
sumaPalamud = kgPalamud * cenaPalamud
cenaSafrid = cenaCaca + cenaCaca * 0.80
sumaSafrid = kgSafrid * cenaSafrid
sumaMidi = kgMidi * 7.50
smetka = sumaPalamud + sumaMidi + sumaSafrid
print('%.2f'%(smetka))