local n = io.read("*n")
local x, y = {}, {}
local parent = {}
for i = 1, n do
  x[i], y[i] = io.read("*n", "*n")
  parent[i] = 0
end

local function getroot(idx)
  while(parent[idx] ~= 0) do
    idx = parent[idx]
  end
  return idx
end

local function getsqlen(idx1, idx2)
  return (x[idx1] - x[idx2]) * (x[idx1] - x[idx2]) + (y[idx1] - y[idx2]) * (y[idx1] - y[idx2])
end

for i = 1, n - 1 do
  for j = i + 1, n do
    if(getsqlen(i, j) <= 100) then
      local ip, jp = getroot(i), getroot(j)
      if(ip ~= jp) then parent[jp] = ip end
      if(ip ~= i) then parent[i] = ip end
      if(ip ~= j) then parent[j] = ip end
    end
  end
end

local rootlist = {}
for i = 1, n do
  local r = getroot(i)
  if(rootlist[r] == nil) then rootlist[r] = {} end
  table.insert(rootlist[r], i)
end

local totmaxlen = 0
for key, val in pairs(rootlist) do
  for i = 1, #val - 1 do
    for j = i + 1, #val do
      totmaxlen = math.max(totmaxlen, getsqlen(val[i], val[j]))
    end
  end
end
if(n == 0) then
  print(1)
else
  print(string.format("%.8f", 2 + math.sqrt(totmaxlen)))
end