local n = io.read("*n", "*l")
local prev = io.read()
local t = {}
t[prev] = true
local ret = true
for i = 2, n do
  local str = io.read()
  if t[str] then
    ret = false
  elseif prev:sub(#prev, #prev) ~= str:sub(1, 1) then
    ret = false
  else
    t[str] = true
    prev = str
  end
end
print(ret and "Yes" or "No")
