import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n,m = na()
dp = [[0 for j in range(m+1)]for i in range(n+1)]
dp[0][0] = 1
mod = 998244353
for i in range(n+1):
    for j in range(m+1):
        if i<n:
            dp[i+1][j] += dp[i][j]
            dp[i+1][j] %= mod
        if j<m:
            dp[i][j+1] += dp[i][j]
            dp[i][j+1] %= mod
        if i<n and j<m:
            dp[i+1][j+1] += 2*dp[i][j]
            dp[i+1][j+1] %= mod
#print(dp[-1][-1])
ans = 0
for i in range(min(n,m)+1):
    ans += dp[-1-i][-1-i]
    ans %= mod
print(ans)