import Data.List (sort)
import Control.Applicative ((<$>))

empty = 100001 :: Int

pickCandy :: [Int] -> [Int]
pickCandy cs
    | c' > 0    = c' : cr
    | otherwise = cr ++ [empty]
    where
        (c : cr) = cs
        c' = c - 1

pickCandies :: Int -> [Int] -> [Int]
pickCandies 0 cs = cs
pickCandies m cs = pickCandies (m - 1) $ pickCandy cs

main :: IO ()
main = do
    (_ : m : _) <- map read . words <$> getLine
    print . length . filter (== empty) . pickCandies m . sort . map read . words =<< getLine