program main
implicit None
	character*10,allocatable::w(:)
	integer::n,i,j,c,k
	
	read *,n
	
	c = 0
	allocate(w(n))
	
	read *,w
	
	do i = 1,n-1
		do j = i+1,n
			if(w(i) == w(j))then
				c = 1
				print *,"a"
			endif
		enddo
	enddo
	
	do i = 2,n
		k = len_trim(w(i-1))
		if(w(i-1)(k:k) /= w(i)(1:1))then
			c = 1
		endif
	enddo
	
	if(c == 0)then
		print 101,"Yes"
		else
			print 101,"No"
	endif
	
101 format(a)
end program main