module String = struct include String (* @since 4.02.0 *) let init n f = let s = String.create n in for i = 0 to n - 1 do s.[i] <- f i done; s end let () = let n = read_int () in print_endline (if n mod 2 = 0 then String.init (n / 2) (fun _ -> '1') else "7" ^ String.init (n / 2 - 1) (fun _ -> '1'))