local double_check = function(t1)
  if not t1 then
    return false
  end
  local len = #t1
  for i=1, len do
    for j=i+1, len do
      -- print('checking: ' .. i .. ", " .. j)
      if t1[i] == t1[j] then
        return true
      end
    end
  end
  return false
end

local shiritori = function(s1, s2)
  local first = string.sub(s2, 1, 1)
  local last = string.sub(s1, -1)
  --print(first)
  --print(last)
  if first == last then
    return true
  else
    return false
  end
end

local num = io.read("*n")
local data = {}
for i=1, num+1 do
  local str = io.read("*l")
  data[i] = str
end
if double_check(data) then
  print('No')
  os.exit(0)
end

for i=2, #data-1 do
  if not shiritori(data[i], data[i+1]) then
    -- print('checking: ' .. i .. ", " .. i+1)
    print('No')
    os.exit(0)
  end
end
print('Yes')
os.exit(0)