import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val n = sc.nextInt()
    val used = mutableSetOf<String>()
    var pre = ""
    repeat(n) {
        val s = sc.next()
        if (pre != "" && pre.last() != s.first() ||
                used.contains(s)) {
            println("No")
            return
        }
        used.add(s)
        pre = s
    }
    println("Yes")
}