import scala.io.StdIn

object Main extends App {

  val n = StdIn.readLine().toInt
  val words = (0 until n).map(_ => StdIn.readLine())
  val r = words.sliding(2).foldLeft((Map.empty[String, Int], true)) { (acc, lst) =>
    if(acc._2 && lst(0).last == lst(1).head  && !acc._1.contains(lst(0))){
      (acc._1 + (lst(0) -> 1), true)
    } else {
      (Map.empty[String, Int], false)
    }
  }
  println(if(r._2) "Yes" else "No")
  
}
