open Printf
open Scanf

let id x = x

let n = scanf "%d" id
let vs = Array.init n (fun i -> scanf " %s" id)

let first_char s = s.[0]
let last_char s = s.[String.length s - 1]
let add list w = list := w :: !list

let () =
  let list = ref [] in
  let isOk = ref true in
  add list vs.(0);
  for i = 1 to n - 1 do
    (if List.mem vs.(i) !list then
      isOk := false
    else if last_char (List.hd !list) <> first_char vs.(i) then
      isOk := false
    );
    add list vs.(i)
  done;
  print_endline @@ if !isOk then "Yes" else "No"
