import Control.Applicative ((<$>))

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
    n <- readLn
    xs <- map read . words <$> getLine
    print $ minNumOfOps n xs