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)