a, b, c, d, e, f = map(int, input().split())
x = []
x.append(a)
x.append(b)
x.append(c)
x.append(d)
x.append(e)
x.append(f)
x.sort()
del x[0]
del x[-1]
z = 0
for i in range(len(x)):
    z += x[i]
result = z / 4
result2 = "{:.2f}".format(result)
print(result2)