Imports System.Collections.Generic
Imports System.Console

Module Program
    Sub Main()
        Dim N As Integer = NextInt()
        Dim dic As New HashSet(Of String)
        Dim pre As Char = " "c
        Dim flg As Boolean

        For i As Integer = 0 To N - 1
            Dim W As String = ReadLine()

            If i <> 0 AndAlso pre <> W(0) Then flg = True
            If dic.Contains(W) Then flg = True

            dic.Add(W)
            pre = W(W.Length - 1)
        Next

        WriteLine(New String() {"Yes", "No"}(B2I(flg)))
    End Sub

    Function B2I(ok As Boolean) As Integer
        If ok Then Return 1
        Return 0
    End Function

    Function NextInt() As Integer
        Return CInt(NextString())
    End Function

    Function NextString() As String
        Dim result As New List(Of Char)
        Do
            Dim tmp As Integer = Read()
            If tmp < 0 Then Exit Do
            Dim nextChar As Char = Chr(tmp)

            If Not Char.IsWhiteSpace(nextChar) Then
                result.Add(nextChar)
            ElseIf nextChar <> vbCr Then
                Exit Do
            End If
        Loop
        Return New String(result.ToArray())
    End Function

End Module
