module Main where


eval :: Int -> Int -> [Int] -> [Int]
eval 0 _ = id
eval t d = eval (t - 1) d . filt . (>>= \x -> [x+d, x, x-d]) where
    filt [] = []
    filt (x:xs) = x : filt (filter (/= x) xs)

main :: IO ()
main = do
        [_, d, t] <- fmap (map read . words) getLine
        xs <- fmap (map read . words) getLine
        print $ length $ eval t d xs