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
}

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

def f(cr)
  P.each do |x, y|
    r = Math.sqrt((x - CX) ** 2 + (y - CY) ** 2)

    return false if cr < r
  end

  true
end

geta = (10 ** 10).to_f
ok = 1000 * geta
ng = 0

while (ok - ng).abs > 1
  mid = (ok + ng) / 2
  cr = mid / geta

  if f(cr)
    ok = mid
  else
    ng = mid
  end
end

puts ok / geta
