import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as B

main = do
 [sa,pa,_] <- B.words <$> B.getLine
 [sb,pb,_] <- B.words <$> B.getLine
 let sa' = B.unpack sa
 let sb' = B.unpack sb
 let pa' = (fst . fromJust . B.readInteger) pa
 let pb' = (fst . fromJust . B.readInteger) pb
 putStrLn (if pa'>pb' then sa' else if pa'<pb' then sb' else "-1")