let rec insert i line lines =
  match lines with
    [] -> line.[i] <- '>'; line.[i+1] <- '<'
  | l :: tail ->
      if l.[i] = '|' && l.[i+1] = '|' then
        insert i l tail
      else begin
          line.[i] <- '>'; line.[i+1] <- '<'
        end
        
let _ =
  let count = ref 0 in
  let lines = ref [] in
  let ic = stdin in
  try
    while true do
      let line = input_line ic in
      let len = String.length line in
      let good = len > 0 && 
        match line.[0] with
          '|' | '<' | '>' -> true
        | _ -> false in
      if not good then () else
      let line = line in
      
      let rec iter i removed =
        if i = len then removed else
        let c = line.[i] in
        if c = '>' then begin
            begin
              try
                line.[i+1] <- '|';
                line.[i] <- '|';
                insert i line !lines;
              with e -> 
                  Printf.fprintf stderr "Error line %d\n" !count;
                  exit 3
            end;
            iter (i+1) removed
          end else
        if c = '<' then 
          iter (i+1) false
        else
          iter (i+1) removed
      in
      let removed = iter 0 true in
      if not removed then
        lines := line :: !lines;
      incr count;
    done;
  with End_of_file ->
      Printf.printf "bbarker\nplinko\nverify\n";
      List.iter (fun s ->
          Printf.printf "%s\n" s
      ) (List.rev !lines);
      print_newline () ;
      print_endline "foo";
      print_endline "bar"