import Control.Applicative ((<$>))
import Data.Char (isSpace)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B
import Data.List (foldl', unfoldr)

getL :: (ByteString -> [Int]) -> IO [Int]
getL f = f <$> B.getLine

readIL :: (ByteString -> Maybe (Int, ByteString)) -> (ByteString -> [Int])
readIL f = unfoldr g
    where
        g s = do
            (n, s') <- f s
            return (n, B.dropWhile isSpace s')

main :: IO ()
main = do
    B.getLine
    as <- reverse <$> getL (readIL B.readInt)
    print $ foldl' f 1 as
    where
        f :: Int -> Int -> Int
        f acc n | acc == 1  = n
                | acc <= n  = acc - 1
                | otherwise = acc