import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe (fromJust)
import Text.Printf
import Debug.Trace

readInts :: B.ByteString -> [Int]
readInts = map (fst . fromJust . B.readInt) . B.words

getInts :: IO [Int]
getInts = liftM readInts B.getLine

f xss n = filter ok [0..(n-1)]
  where
    ok i = and $ map (\j -> xss!!j!!i == "nyanpass"
                              || xss!!j!!i == "-") [0..(n-1)]

printAns xs = if length xs == 1 
              then print $ 1 + head xs
              else print (-1)

main = do
  [n] <- getInts
  xss <- fmap words <$> replicateM n getLine
  printAns $ f xss n