-- https://github.com/minoki/my-atcoder-solutions
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
import Data.Char (isSpace)
import Data.Int (Int64)
import Data.List (unfoldr)
import qualified Data.Vector.Unboxed as U
import qualified Data.Vector.Unboxed.Mutable as UM
import qualified Data.ByteString.Char8 as BS
import Data.Coerce
import qualified Data.Vector.Generic
import qualified Data.Vector.Generic.Mutable

solve :: Int -> Int -> N
solve !n !m = let mk = (3*m) `quot` 2
                  ts = U.scanl' (+) 0 $ U.map (\l -> binom (l+n-2) (n-2)) $ U.enumFromN 0 (mk-m)
              in sum [ binom (k+n-1) (n-1) * binom n (3*m-2*k) - fromIntegral n * (binom n (3*m-2*k) * ts U.! (k-m) + binom (k-m+n-2) (n-2) * binom (n-1) (3*m-2*k-1))
                     | k <- [m..mk]
                     , let t | k-m >= 0 = ts U.! (k-m)
                             | otherwise = 0
                     ]

main = do
  [n,m] <- unfoldr (BS.readInt . BS.dropWhile isSpace) <$> BS.getLine
  print $ solve n m

factV :: U.Vector N
factV = U.scanl' (*) 1 (U.enumFromN 1 (25*10^5))

binom :: Int -> Int -> N
binom n k | k < 0 || k > n = 0
          | otherwise = factV U.! n / (factV U.! (n-k) * factV U.! k)

--
-- Modular Arithmetic
--

modulo :: Int64
modulo = 998244353
addMod, subMod, mulMod :: Int64 -> Int64 -> Int64
addMod !x !y | x + y >= modulo = x + y - modulo
             | otherwise = x + y
subMod !x !y | x >= y = x - y
             | otherwise = x - y + modulo
mulMod !x !y = (x * y) `rem` modulo

newtype N = N { unwrapN :: Int64 } deriving (Eq)
instance Show N where
  show (N x) = show x
instance Num N where
  (+) = coerce addMod
  (-) = coerce subMod
  (*) = coerce mulMod
  fromInteger n = N (fromInteger (n `mod` fromIntegral modulo))
  abs = undefined; signum = undefined

{-# RULES
"^9/Int" forall x. x ^ (9 :: Int) = let u = x; v = u * u * u in v * v * v
"^9/Integer" forall x. x ^ (9 :: Integer) = let u = x; v = u * u * u in v * v * v
 #-}

---

exEuclid :: (Eq a, Integral a) => a -> a -> (a, a, a)
exEuclid !f !g = loop 1 0 0 1 f g
  where loop !u0 !u1 !v0 !v1 !f 0 = (f, u0, v0)
        loop !u0 !u1 !v0 !v1 !f g =
          case divMod f g of
            (q,r) -> loop u1 (u0 - q * u1) v1 (v0 - q * v1) g r

recipM :: Int64 -> Int64
recipM !x = case exEuclid x modulo of
             (1,a,_) -> a `mod` modulo
             (-1,a,_) -> (-a) `mod` modulo
divM :: Int64 -> Int64 -> Int64
divM !x !y = x `mulMod` recipM y

instance Fractional N where
  (/) = coerce divM
  recip = coerce recipM
  fromRational = undefined

---

newtype instance UM.MVector s N = MV_N (UM.MVector s Int64)
newtype instance U.Vector N = V_N (U.Vector Int64)

instance Data.Vector.Generic.Mutable.MVector UM.MVector N where -- needs MultiParamTypeClasses here
  basicLength (MV_N mv) = Data.Vector.Generic.Mutable.basicLength mv
  basicUnsafeSlice i l (MV_N mv) = MV_N (Data.Vector.Generic.Mutable.basicUnsafeSlice i l mv)
  basicOverlaps (MV_N mv) (MV_N mv') = Data.Vector.Generic.Mutable.basicOverlaps mv mv'
  basicUnsafeNew l = MV_N <$> Data.Vector.Generic.Mutable.basicUnsafeNew l
  basicInitialize (MV_N mv) = Data.Vector.Generic.Mutable.basicInitialize mv
  basicUnsafeReplicate i x = MV_N <$> Data.Vector.Generic.Mutable.basicUnsafeReplicate i (coerce x)
  basicUnsafeRead (MV_N mv) i = coerce <$> Data.Vector.Generic.Mutable.basicUnsafeRead mv i
  basicUnsafeWrite (MV_N mv) i x = Data.Vector.Generic.Mutable.basicUnsafeWrite mv i (coerce x)
  basicClear (MV_N mv) = Data.Vector.Generic.Mutable.basicClear mv
  basicSet (MV_N mv) x = Data.Vector.Generic.Mutable.basicSet mv (coerce x)
  basicUnsafeCopy (MV_N mv) (MV_N mv') = Data.Vector.Generic.Mutable.basicUnsafeCopy mv mv'
  basicUnsafeMove (MV_N mv) (MV_N mv') = Data.Vector.Generic.Mutable.basicUnsafeMove mv mv'
  basicUnsafeGrow (MV_N mv) n = MV_N <$> Data.Vector.Generic.Mutable.basicUnsafeGrow mv n

instance Data.Vector.Generic.Vector U.Vector N where -- needs MultiParamTypeClasses here
  basicUnsafeFreeze (MV_N mv) = V_N <$> Data.Vector.Generic.basicUnsafeFreeze mv
  basicUnsafeThaw (V_N v) = MV_N <$> Data.Vector.Generic.basicUnsafeThaw v
  basicLength (V_N v) = Data.Vector.Generic.basicLength v
  basicUnsafeSlice i l (V_N v) = V_N (Data.Vector.Generic.basicUnsafeSlice i l v)
  basicUnsafeIndexM (V_N v) i = coerce <$> Data.Vector.Generic.basicUnsafeIndexM v i
  basicUnsafeCopy (MV_N mv) (V_N v) = Data.Vector.Generic.basicUnsafeCopy mv v
  elemseq (V_N v) x y = Data.Vector.Generic.elemseq v (coerce x) y

instance U.Unbox N


Measured memory_bytes: 46076