import Data.List
import Data.Ord
import Data.Char
import Data.Ratio
import Data.Maybe

main = do
  getLine
  s <- lines <$> getContents
  putStrLn $ shiritori s
  
shiritori l
  |(length .foldl1 intersect)l/=0 = "No"
  |otherwise = shiritori2 l

shiritori2 (_:[]) = "Yes"
shiritori2 (x:y:ys)
  |last x==head y = shiritori2 (y:ys)
  |otherwise = "No"