a, b, c, d, e = float(input()), float(input()), float(input()), float(input()), float(input())
mx = max(a, b, c, d, e)
mn = min(a, b, c, d, e)
pr = 1
if a != mx and a != mn:
    pr = a * pr
if b != mx and b != mn:
    pr = b * pr
if c != mx and c != mn:
    pr = c * pr
if d != mx and d != mn:
    pr = d * pr
if e != mx and e != mn:
    pr = e * pr
med = round(pr / 3, 2)
print(med)