S=[int(i) for i in input().split()]
Mi=S[0]
Ma=S[0]
Su=S[0]
i=1
while i<6:
    Su+=S[i]
    if Mi>S[i]:
        Mi=S[i]
    if S[i]>Ma:
        Ma=S[i]
    i+=1
Su=Su-Mi-Ma
Su/=4
print ("{0:.2f}".format(Su))