let _ =
  let cipher str = String.map (fun c -> if c = 'z' then 'a' else if c >= 'a' && c <= 'y' then char_of_int (int_of_char c + 1) else c) str in
  let elem s1 s2 =
    let l = String.length s2 in
    let rec iter i = 
      try
        let s = String.sub s1 i l in
        if String.compare s s2 = 0 then true else iter (i + 1)
      with
        Invalid_argument _ -> false in
    iter 0 in
  let rec iter str =
    if (elem str "this") || (elem str "that") || (elem str "the") then print_endline str
    else iter (cipher str) in
  try
    while true do
      let str = read_line () in
      iter str
    done
  with
    End_of_file -> ()