"""

AA_DELETE_BB　想定解v1

"""

import sys
from sys import stdin


def modfac(n, MOD):
 
    f = 1
    factorials = [1]
    for m in range(1, n + 1):
        f *= m
        f %= MOD
        factorials.append(f)
    inv = pow(f, MOD - 2, MOD)
    invs = [1] * (n + 1)
    invs[n] = inv
    for m in range(n, 1, -1):
        inv *= m
        inv %= MOD
        invs[m - 1] = inv
    return factorials, invs

def modnCr(n,r):
    return fac[n] * inv[n-r] * inv[r] % mod

x,y = map(int,stdin.readline().split())
mod = 998244353
fac,inv = modfac(x+y+10,mod)

#制約チェック
assert 1 <= x <= 4000
assert 1 <= y <= 4000

bpow = [1]
for i in range(x+y+10):
    bpow.append(bpow[-1] * 2 % mod)

ans = 0

for P in range(min(x,y) + 1):

    qmax = min(x,y) - P

    for Q in range(qmax+1):

        ans += bpow[Q] * modnCr(x+y-2*P-Q,Q) * modnCr(x+y-2*P-2*Q,x-P-Q)
        ans %= mod

print (ans % mod)