N = gets.to_i
P = N.times.map { gets.split.map(&:to_i) }

def ternary_search_tree(left, right)
  loop_cnt = 10000

  loop_cnt.times do
    if yield((left * 2 + right) / 3.0) < yield((left + right * 2) / 3.0)
      right = (left + right * 2) / 3.0
    else
      left = (left * 2 + right) / 3.0
    end
  end

  (left + right) / 2.0
end

CX = ternary_search_tree(-10000, 10000) { |n|
  P.map { |x, _| (x - n).abs }.max
}

CY = ternary_search_tree(-10000, 10000) { |n|
  P.map { |_, y| (y - n).abs }.max
}

cy = P.map(&:first).inject(:+) / N.to_f
cx = P.map(&:last).inject(:+) / N.to_f

r = P.map { |x, y| Math.sqrt((x - CX) ** 2 + (y - CY) ** 2) }.max
r2 = P.map { |x, y| Math.sqrt((x - cx) ** 2 + (y - cy) ** 2) }.max

puts [r, r2].min
