import math

p1 = [int(x) for x in input().split(" ")]
p2 = [int(x) for x in input().split(" ")]
p3 = [int(x) for x in input().split(" ")]


def to_r(x,y):
    return [math.atan2(x, y), math.sqrt(x**2 + y**2)]

def to_c(a,r):
    return [math.cos(a) * r, math.sin(a) * r]


d_min = None
for (a, b, c) in [(p1, p2, p3), (p1, p3, p2), (p2, p3, p1)]:

    m_x = float(a[0] + b[0]) / 2
    m_y = float(a[1] + b[1]) / 2


    a_a, a_r = to_r(a[0] - m_x, a[1] - m_y)
    b_a, b_r = to_r(b[0] - m_x, b[1] - m_y)
    
    c_a, c_r = to_r(c[0] - m_x, c[1] - m_y)


    sh = (math.pi * 3) / 2 - a_a 
    
    a_ = to_c(a_a + sh, a_r)
    b_ = to_c(b_a + sh, b_r)
    c_ = to_c(c_a + sh, c_r)



    # print(a_, b_, c_)

    d1 = abs(c_[1] - b_[1])
    d2 = abs(c_[1] - a_[1])
    
    sx = (a_[0] + b_[0]) / 2
    sy = (a_[1] + b_[1]) / 2

    d3 = abs(abs(sy - a_[1]) - math.sqrt(c_[0] ** 2 + (c_[1] - sy) ** 2))


    lm = min(d1,d2,d3)
    if d_min is None or lm < d_min:
        d_min = lm

print(d_min)