import math

x1, y1 = [int(x) for x in input().split(" ")]
x2, y2 = [int(x) for x in input().split(" ")]
x3, y3 = [int(x) for x in input().split(" ")]

def s(x1, y1, x2, y2):
    return 0.5 * (x1 + x2), 0.5 * (y1 + y2)

def l(x1, y1, x2, y2):
    return math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2)


s12 = s(x1, y1, x2, y2)
s13 = s(x1, y1, x3, y3)
s23 = s(x2, y2, x3, y3)

p1s23 = l(x1, y1, *s23)
p2s13 = l(x2, y2, *s13)
p3s12 = l(x3, y3, *s12)

r12 = l(x1, y1, *s12)
r13 = l(x1, y1, *s13)
r23 = l(x2, y2, *s23)

ret = min(
    abs(p3s12 - r12),
    abs(p2s13 - r13),
    abs(p1s23 - r23)
)

print(ret)