program main
  implicit integer(a-z)
  character(10), dimension(100)::w
  character(3)::ans="Yes"

  read(*,*)n
  do i=1,n
     read(*,*)w(i)
  end do

  do i=2,n
     
     if(w(i-1)(len(trim(adjustl(w(i-1)))):len(trim(adjustl(w(i-1)))))&
          .ne.w(i)(1:1))then
        ans="No"
        write(*,*)i
     end if
 
     do j=1,i-1
        if(w(j).eq.w(i))then
           ans="No"
           !write(*,*)i,j
        end if
     end do
  end do
 
  write(*,*)ans
end program main