module Main where

import Control.Monad
import Data.List (transpose)

main :: IO ()
main = do
    n <- readLn
    xss <- fmap transpose . replicateM n $ words <$> getLine
    let f x = if (x == "-" || x == "nyanpass") then True else False
    let ys = filter ((all f) . snd) $ zip [1..] xss
    if length ys == 1
        then print $ fst $ head ys
        else print (-1)