N, M = map(int, input().split())
S = [input() for _ in range(N)]

a = [[0, 0] for _ in range(3)]

for i in range(N):
	for j in range(M):
		if S[i][j] == "B": a[(i+j)%3][0] += 1
		elif S[i][j] == "?": a[(i+j)%3][1] += 1

ans = [[0, 0] for _ in range(3)]
for i in range(3):
	if a[i][1] == 0:
		ans[i][(a[i][0]+1)%2] = -10000000
	else:
		ans[i][0] = a[i][1]-1
		ans[i][1] = a[i][1]-1

#print(ans)
cnt = max(ans[0][0]+ans[1][0]+ans[2][0], ans[0][1]+ans[1][1]+ans[2][1])
#print(cnt)
if cnt < 0: print(0)
else: print(pow(2, cnt, 998244353))