class union_find n = object(self)
  val father = Array.make n -1
  val count = Array.make n 1
  method find i = if father.(i) = -1 then i else self#find(father.(i))
  method union i j =
    let i0 = self#find i in
    let j0 = self#find j in
      if i0 <> j0 then 
	begin
	  ....
	end
end;;