N = gets.to_i
coords = $<.map{|s|
  x, y = s.split.map &:to_f
  [x, y]
}
if N == 2
(x, y), (xx, yy) = coords
  p ((x - xx) ** 2 + (y - yy) ** 2) ** 0.5 / 2
  exit
end

ans = 1.0/0
coords.combination(3).each{|(a, b), (c, d), (e, f)|
  if a == c && c == e
    x = a
    ymin, ymax = [b, d, f].minmax
    y = (ymax + ymin) / 2
    r = (ymax - ymin) / 2
  elsif b == d && d == f
    y = b
    xmin, xmax = [a, c, e].minmax
    x = (xmax + xmin) / 2
    r = (xmax - xmin) / 2
  else
    x1, y1, x2, y2, x3, y3 = a,b,c,d,e,f
    a = ((x2-x1)**2 + (y2-y1)**2)**0.5
    b = ((x3-x2)**2 + (y3-y2)**2)**0.5
    c = ((x1-x3)**2 + (y1-y3)**2)**0.5
  
    a1 = 2*(x2 - x1)
    b1 = 2*(y2 - y1)
    c1 = x1**2 - x2**2 + y1**2 - y2**2
    a2 = 2*(x3 - x1)
    b2 = 2*(y3 - y1)
    c2 = x1**2 - x3**2 + y1**2 - y3**2
  
    x = (b1*c2 - b2*c1) / (a1*b2 - a2*b1)
    y = (c1*a2 - c2*a1) / (a1*b2 - a2*b1)
    r = (a*b*c) / (((a+b+c)*(b+c-a)*(c+a-b)*(a+b-c))**0.5)
  end
  ans = r if coords.all?{|xx, yy|
    ((x - xx) ** 2 + (y - yy) ** 2) ** 0.5 <= r+0.000000001
  } && r < ans
}
p ans