N=io.read("n")
s={}
for i=1,N do 
  s[i]=io.read()
end
res="Yes"
for i=1,N-1 do
  if string.sub(s[i],#s[i],#s[i])~=string.sub(s[i+1],1,1) then
    res="No"
  end
end
table.sort(s)
for i=1,N-1 do
  if s[i]==s[i+1] then
    res="No"
  end
end
print(res)
