n = gets.to_i
x = []
y = []
for i in 0...n do
  x[i], y[i] = gets.split.map(&:to_i)
end
max_d = 0
for i in 0...(n - 1) do
  for j in (i + 1)...n do
    d = Math.sqrt((x[i] - x[j]) ** 2 + (y[i] - y[j]) ** 2)
    max_d = d if max_d < d
  end
end
puts max_d / 2
