mod=998244353
two=[1 for _ in range(10**5+1)]
for i in range(1,10**5) : two[i]=two[i-1]*2%mod

from itertools import product
H,W=map(int,input().split())
A=[input() for _ in range(H)]
xor=[0 for _ in range(9)]
und=[0 for _ in range(9)]
for i,j in product(range(H),range(W)):
    if A[i][j]=="B" : xor[(i%3)*3+j%3]^=1
    elif A[i][j]=="?" : und[(i%3)*3+j%3]+=1

ans=0
def f(n) : return (t>>n)%2
def r(p1,p2,p3) : global t ; t^=(1<<p1) ; t^=(1<<p2) ; t^=(1<<p3)
for t in range(2**9):
    v=t
    if f(2) : r(0,1,2)
    if f(5) : r(3,4,5)
    if f(8) : r(6,7,8)
    if f(6) : r(0,3,6)
    if f(7) : r(1,4,7)
    if t in [0,10,19,25]:
        cnt=1
        for i in range(9):
            if xor[i]!=(v>>i)%2 and und[i]==0 : cnt=0
            else : cnt=cnt*two[und[i]-1]
        ans+=cnt
print(ans%mod)