from math import sqrt

x1, y1 = map(int, input().split())
x2, y2 = map(int, input().split())
x3, y3 = map(int, input().split())

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

data = [(x1, y1), (x2, y2), (x3, y3)]
m = float('+inf')
for i, (x0, y0) in enumerate(data):
    (x1, y1), (x2, y2) = data[:i] + data[i + 1:]

    center = ((x1 + x2) / 2, (y1 + y2) / 2)
    r = get_distance(x1, y1, center[0], center[1])
    l = get_distance(x0, y0, center[0], center[1])
    m = min(m, abs(l - r))


print(m)