import scala.io.StdIn._

/**
 * ABC109B
 */
object Main extends App {

  val n = readInt()
  val strs = (0 until n).map(_ => readLine()).toSeq

  val f = (strs: Seq[String]) => {
    val set = scala.collection.mutable.Set[String]()
    var past: String = strs(0)(0).toString()
    var flag = true

    for (s <- strs) {
      if (set.contains(s)) flag = false
      set += s
      if (past(past.length() - 1) != s(0)) flag = false
      past = s
    }
    if (flag) "Yes"
    else "No"
  }

  val ans = f(strs)

  println(ans)
}
