import Data.List
main = getLine >> getLine >>= main' . map read . words
        where
                main' xs = getLine >>= putStrLn . solve . zip xs . map read . words

solve :: [(Int, Int)] -> String
solve xs
        | acc < mnum = "NO"
        | otherwise = "YES"
        where
                (acc, mnum) = foldl ff (0, 0) xs

ff :: (Int, Int) -> (Int, Int) -> (Int, Int)
ff (acc, mnum) (x, y)
        | y == 0 = (acc + x, max mnum x)
        | otherwise = (acc, max mnum x)