import qualified Data.Map as M

main = getLine >> getLine >>= main' . map read . words
        where
                main' xs = getLine >>= putStrLn . solve . M.fromListWith (+) . flip zip xs . map read . words

solve :: M.Map Int Int -> String
solve xs
        | k < mnum = "NO"
        | otherwise = "YES"
        where
                mnum = M.foldl max 0 xs
                k = err $ M.lookup 0 xs
                err (Just x) = x
                err _ = (-1)