import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = println(solve(new Scanner(System.in)))

  def solve(in: String): String = solve(new Scanner(in))

  def solve(sc: Scanner): String = {
    val N = sc.nextInt
    val W = Array.fill(N)(sc.next)

    if (W.distinct.length != W.length) {
      return "No"
    }

    var last = W(0).head
    W.foreach { w =>
      if (w.head != last) {
        return "No"
      }
      last = w.last
    }
    "Yes"
  }
}
