local mma = math.max
local msq = math.sqrt
local n = io.read("*n")
local x, y = {}, {}
for i = 1, n do
  x[i], y[i] = io.read("*n", "*n")
end
local rep = 1000

local tx, ty = 0, 0
local function solvex(px)
  tx = px
  local sq = 0
  for i = 1, n do
    local tmp = (tx - x[i]) * (tx - x[i]) + (ty - y[i]) * (ty - y[i])
    sq = mma(sq, tmp)
  end
  return sq
end

local function triplediv(xmin, xmax, rep, func)
  local left_v, right_v = func(xmin), func(xmax)
  for i = 1, rep do
    local xmid1, xmid2 = (xmin * 2 + xmax) / 3, (xmin + xmax * 2) / 3
    local mid_v1, mid_v2 = func(xmid1), func(xmid2)
    if left_v > mid_v1 then
      if mid_v2 > right_v then
        xmin = xmid2
        left_v = mid_v2
      elseif mid_v1 > mid_v2 then
        xmin = xmid1
        left_v = mid_v1
      else
        xmax = xmid2
        right_v = mid_v2
      end
    else
      if mid_v2 < right_v then
        xmax = xmid1
        right_v = mid_v1
      elseif mid_v1 < mid_v2 then
        xmin = xmid1
        left_v = mid_v1
      else
        xmax = xmid2
        right_v = mid_v2
      end
    end
  end
  return (left_v + right_v) / 2
end

local function solvey(py)
  ty = py
  return triplediv(0, 1000, rep, solvex)
end

local ret = triplediv(0, 1000, rep, solvey)
print(string.format("%.10f", msq(ret)))
