a = io.read()
a = tonumber(a)
s = {}
flag = "Yes"
last = nil
for i = 1, a do
	b = io.read()
	if s[b] or (last and string.sub(b, 1, 1) ~= last) then
		flag = "No"
	end
	s[b] = true
	last = string.sub(b, #b, #b)
end
print(flag)