import Control.Applicative ((<$>))
import qualified Data.ByteString.Lazy.Char8 as LC
import Data.Maybe (fromJust)

minNumOfOps :: Integral a => a -> [a] -> a
minNumOfOps n xs = mnoo n $ reverse xs
    where
        mnoo t [] = t
        mnoo t (y : ys)
            | y == t    = flip mnoo ys $ t - 1
            | otherwise = mnoo t ys

main :: IO ()
main = do
    d <- map (fst . fromJust . LC.readInt) . LC.words <$> LC.getContents
    print $ minNumOfOps (head d) $ tail d