import Data.List
import Control.Monad

main :: IO ()
main = do
    n <- readLn :: IO Int
    xss <- replicateM n $ words <$> getLine :: IO [[String]]
    let ys = map (length . filter (/= "nyanpass") . filter (/= "-" )) $ transpose xss
        t  = length $ filter (== 0) ys
        zs = zip [1..n] ys
    if t == 1 then print $ fst $ head $ filter (\(a, b) -> b == 0) zs
              else print (-1)