import Data.List
import Control.Applicative
import Control.Monad

main = do
  n <- readLn
  names <- replicateM n getLine
  let perm1 = permutations "iaaeuu"
      perm2 =  permutations "nbgmr*"
      newNames = [ins c v | v <- perm1, c <- perm2] \\ names
  case newNames of
      [] -> putStrLn "NO"
      _ -> putStrLn $ head newNames

ins [] [] = ""
ins ('*' : cs) (v : vs) = v : ins cs vs
ins (c : cs) (v : vs) = c : v : ins cs vs