from math import sqrt

ax, ay = map(int, input().split())
bx, by = map(int, input().split())
cx, cy = map(int, input().split())
res = 1e9

def dist(x1, y1, x2, y2):
    return sqrt(((x1 - x2) ** 2) + ((y1 - y2) ** 2))

for i in range(3):
    sx, sy = (ax + bx) / 2, (ay + by) / 2
    cs = dist(cx, cy, sx, sy)
    ab = dist(ax, ay, bx, by)
    r = ab / 2
    res1 = abs(cs - r)
    res = min(res, res1)

    ax, ay, bx, by, cx, cy = bx, by, cx, cy, ax, ay


print(res)