output_description: Print the minimum radius of a circle such that all the N points are inside or
  on it.
  
  Your output will be considered correct if the absolute or relative error from
  our answer is at most 10^{-6}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      x_1 y_1
      :
      x_N y_N
attempt: N = int(input())
  XY = [complex(*map(int, input().split())) for _ in range(N)]
  ans = 10**18
  
  
  def calc(center):
      return max(abs(center - x) for x in XY)
  
  
  for A in XY:
      for B in XY:
          center = (A + B) / 2
          ans = min(ans, calc(center))
  
          for C in XY:
              a, b, c = abs(B - C), abs(C - A), abs(A - B)
  
              S = 0
              T = complex(0, 0)
              for (x, y, z), u in zip([(a, b, c), (b, c, a), (c, b, a)], (A, B, C)):
                  O = x**2 * (y**2 + z**2 - x**2)
                  S += O
                  T += O * u
  
              if S == 0:
                  continue
              ans = min(ans, calc(T / S))
  
  print(ans)
  
problem_description: Statement
  
  Given are N points (x_i, y_i) in a two-dimensional plane.
  
  Find the minimum radius of a circle such that all the points are inside or on
  it.
samples: [{"input": "2\n    0 0\n    1 0", "output": "0.500000000000000000\n    \n\nBoth points are contained in the circle centered at (0.5,0) with a radius of\n0.5.\n\n* * *"}, {"input": "3\n    0 0\n    0 1\n    1 0", "output": "0.707106781186497524\n    \n\n* * *"}, {"input": "10\n    10 9\n    5 9\n    2 0\n    0 0\n    2 7\n    3 3\n    2 5\n    10 0\n    3 7\n    1 9", "output": "6.726812023536805158\n    \n\nIf the absolute or relative error from our answer is at most 10^{-6}, the\noutput will be considered correct."}]