a, b, c, d, e, f = map(int, input().split())
f -= e
e = 0
assert a == b
c /= a
d /= a
f /= a
a = 1
b = 1
x0 = -c * 0.5
y0 = -d * 0.5
f += x0 ** 2 + y0 ** 2
print(f ** 0.5)