require 'set'

Problem168 = Struct.new(:points) do
  def solve
    @distance_cache = []
    w = isqrt(squared_distance_by_index(0, points.size - 1)) / 10
    p 10 * (1..w + 1).bsearch {|d| reach? d }
  end

  private

  def isqrt(x)
    (1..x).bsearch {|r| x <= r ** 2 }
  end

  def reach?(d)
    sqlen = (d * 10) ** 2
    goal = points.size - 1
    stack = [0]
    todo = Set.new(1..goal)
    while i = stack.pop
      todo.each do |j|
        if squared_distance_by_index(i, j) <= sqlen
          return true if j.equal?(goal)
          todo.delete j
          stack << j
        end
      end
    end
    false
  end

  def squared_distance_by_index(ia, ib)
    ia, ib = ib, ia if ib < ia
    @distance_cache[ia * points.size + ib] ||= squared_distance(points[ia], points[ib])
  end

  def squared_distance(a, b)
    ax, ay = a
    bx, by = b
    (ax - bx) ** 2 + (ay - by) ** 2
  end
end

Problem168.new((1..gets.to_i).map{gets.split.map(&:to_i)}).solve