mod = 998244353

N, M = map(int, input().split())
if N % 2 == 1:
	if (M + 1) % mod == 0:
		print((N - 1) % mod)
	else:
		print(((pow(M, N, mod) + 1) * pow(M + 1, mod - 2, mod) - 1) % mod)
else:
	if (M + 1) % mod == 0:
		print((-N + 1) % mod)
	else:
		print(((pow(M, N, mod) - 1) * pow(M + 1, mod - 2, mod) + 1) % mod)