import Control.Monad
import Data.Array.IO
import Data.Array.Unboxed

type Idx = (Int,Int)
type IODp = IOUArray Idx Int

main = do
    [n,a] <- map read.words<$>getLine::IO[Int]
    ys <- map (flip(-)a.read).words<$>getLine::IO[Int]
    let nx = n * maximum (a:ys)
    dp <- newArray ((0,-nx),(n,nx)) 0 :: IO IODp
    mapM_ (f dp nx) [(j,t)|j<-zip [0..] (0:ys), t<-[-nx..nx]]
    print.flip(-)1 =<< readArray dp (n,0)

f dp _ ((0,_),0) = writeArray dp (0,0) 1
f dp nx ((j,yj),t) | j>0, -nx<=t-yj, t-yj<=nx = liftM2 (+) (readArray dp (j-1,t)) (readArray dp (j-1,t-yj)) >>= writeArray dp (j,t)
f dp _ ((j,yj),t) | j>0 = readArray dp (j-1,t) >>= writeArray dp (j,t)
f _ _ _ = return ()

{-
dp(j,t) -> [y1..yj]から合計をtにするような選び方の総数, -nx<=t<=nx

dp(0,0) = 1
dp(j,t) = dp(j-1,t) + dp(j-1,t-yj) , j>=1, -nx <= t-yj <= nx
dp(j,t) = dp(j-1,t)                , j>=1
other = 0
-}