fun main(args: Array<String>) {
    val mod = 1000000007
    val N = readInt()
    val w = readString()
    val set = mutableSetOf(w)
    var last = w.last()
    var ans = "Yes"
    for(n in 0 until N-1) {
        val w = readString()
        if (w.first() != last || w in set) ans = "No"

        set.add(w)
        last = w.last()
    }
    println(ans)
}

fun readString() = readLine()!!
fun readInt() = readLine()!!.toInt()
fun readLong() = readLine()!!.toLong()
fun readIntList() = readLine()!!.split(" ").map(String::toInt)
fun readLongList() = readLine()!!.split(" ").map(String::toInt)