local a, b, c = io.read("*n", "*n", "*n")
local d, e, f = io.read("*n", "*n", "*n")
c, d, e, f = c / a, d / a, e / a, f / a
z = math.sqrt(f - e + c * c / 4 + d * d / 4)
print(string.format("%.12f", z))