h,w=map(int,input().split())
c=[0]*3
f=[0]*3
for i in range(h):
  s=input()
  for j in range(w):
    c[(i+j)%3]+=s[j]=="?"
    f[(i+j)%3]^=s[j]=="B"
if sum(c[i]==0 and f[i]==0 for i in range(3))>0 and sum(c[i]==0 and f[i]==1 for i in range(3))>0:
  print(0)
  exit()
M=998244353
g=1
for v in c:
  if v>0:
    g*=pow(2,v-1,M)
    g%=M
if all(v>0 for v in c):
  g*=2
  g%=M
print(g)