let () =
  let n = read_float () in
  let rec read minf maxf =
        try let n = read_float () in
            let x = if minf > n then n else minf and
                y = if maxf < n then n else maxf in
            read x y
        with End_of_file ->
          print_float (maxf -. minf);
          print_newline ()
  in read n n;;