Module _20190423

    Sub Main()

        Dim iCount As Integer = Console.ReadLine()

        Dim sWord(iCount - 1) As String

        sWord(0) = Console.ReadLine()

        Dim sLastChar As String = sWord(0).ToCharArray(sWord(0).Length - 1, 1)

        Dim iNGFlg As Integer = 0
        For i As Integer = 1 To iCount - 1

            sWord(i) = Console.ReadLine()

            If sLastChar = sWord(i).ToCharArray(0, 1) Then

                For j As Integer = 0 To i - 1

                    If sWord(j) = sWord(i) Then

                        iNGFlg = 1

                        Exit For

                    End If

                Next

            Else

                iNGFlg = 1

            End If

            If iNGFlg = 1 Then

                Exit For

            Else

                sLastChar = sWord(i).ToCharArray(sWord(i).Length - 1, 1)

            End If

        Next

        If iNGFlg = 1 Then

            Console.WriteLine("No")

        Else

            Console.WriteLine("Yes")

        End If

    End Sub

End Module