let id x = x

let rec read () =
  try
    let x = Scanf.scanf "%f\n" id in x :: read ()
  with
    End_of_file -> []

let _ = 
  let lst = read () in
  let f (l, m) x = ((if l = 0.0 then x else max l x), (if m = 0.0 then x else min m x)) in
  let mx, mn = List.fold_left f (0.0, 0.0) lst in
  Printf.printf "%f\n" (mx -. mn)