N, M = map(int, input().split())
S = [input() for _ in range(N)]
c = [0] * 3
d = [0] * 3
for i in range(N):
	for j in range(M):
		if S[i][j] == 'B':
			c[(i + j) % 3] ^= 1
		if S[i][j] == '?':
			d[(i + j) % 3] += 1
# print(c)
# print(d)
ans_0 = 1
mod = 998244353
for i in range(3):
	if d[i] == 0 and c[i] == 1:
		ans_0 = 0
	elif d[i] >= 1:
		ans_0 *= pow(2, d[i] - 1, mod)
		ans_0 %= mod
ans_1 = 1
mod = 998244353
for i in range(3):
	if d[i] == 0 and c[i] == 0:
		ans_1 = 0
	elif d[i] >= 1:
		ans_1 *= pow(2, d[i] - 1, mod)
		ans_1 %= mod

print((ans_0 + ans_1) % mod)