import java.io.{InputStream, OutputStream, PrintStream}
import java.util.Scanner

object Main {

  def main(args: Array[String]): Unit = {
    val solver = new Solver(System.in, System.out)
    solver.solve()
  }

  class Solver(in: InputStream, out: OutputStream) {
    lazy val input = new Scanner(in)

    lazy val output = new PrintStream(out)

    def solve(): Unit = {
      val n     = input.nextLine().toInt
      val words = 1.to(n).map(_ => input.nextLine())

      val isDuplicate = words.sorted.distinct.size != words.size
      val isConnected = words.sliding(2).forall {
        case Seq(first, second) => first.last == second.head
      }

      if (!isDuplicate && isConnected)
        output.println("Yes")
      else
        output.println("No")
    }

  }

}
