object Main extends App {
    import scala.io.StdIn._
    val n = readLine().toInt
    var w_ar: Array[String] = Array.empty
    for (_ <- 1 to n){
      w_ar = w_ar :+ readLine()
    }

    def hoge(ar: Array[String], nn: Int):String = {
      for (i<-0 to nn-2){
        if (ar(i).last != ar(i+1).head) {
          return "No"
        }
      }
      "Yes"
    }

    if (w_ar.length != w_ar.distinct.length) {
      println("No")
    } else {
      println(hoge(w_ar, n))
    }
}