local n = io.read()
local w = {}
local flag = true
for i=1,n do
	w[i] = io.read()
end

for i = 1, n-1 do
	if string.sub(w[i],-1,-1) ~= string.sub(w[i+1],1,1) then
	flag = false
	end
end

for i = 1,n-1 do
	for j=i+1,n do
		if w[i] == w[j] then
		    flag = false
		end
	end
end

if flag then
	print("Yes")
else
	print("No")
end
--#17024844 | kachidoki's solution for [AtCoder-4252] [Problem B]