let () =
  let s = read_line () in
  print_endline @@
  if
    Array.fold_left ( && ) (String.length s mod 2 = 0) @@
    Array.init (String.length s) @@ fun i ->
      if i mod 2 = 0
      then s.[i] = 'h'
      else s.[i] = 'i'
  then "Yes"
  else "No"