from math import pi, fabs

vert = []
for i in range(3):
    x, y = map(int, input().split())
    vert . append ( ( x, y ) )

# print(vert)

def dist(a, b):
    return ( ( a[0] - b[0]) ** 2 + ( a[1] - b[1]) ** 2 ) ** ( 1/2 )

# print(dist(vert[0], vert[1]))

def middle(a, b):
    x_diff = (b[0] + a[0]) / 2
    y_diff = (b[1] + a[1]) / 2
    return (x_diff, y_diff)

# print(middle((0,0), (0,4)))
# print(middle((-4,0), (0,4)))
# print(middle((0,4), (0,0)))
# print(middle((1,1), (3,3)))

# fixed 0, 1
# calc 2

d = []
mid = middle(vert[0], vert[1])
dist_2 = dist(mid, vert[2])
dist_calc = dist_2 - dist(vert[0], mid)

d.append(fabs(dist_calc))

mid = middle(vert[0], vert[2])
dist_2 = dist(mid, vert[1])
dist_calc = dist_2 - dist(vert[0], mid)

d.append(fabs(dist_calc))

mid = middle(vert[1], vert[2])
dist_2 = dist(mid, vert[0])
dist_calc = dist_2 - dist(vert[1], mid)

d.append(fabs(dist_calc))

# print(d)
print(min(d))