class CP:
    def __init__(self, N):
        self.fact = [1]
        self.fact_inv = [1]
        for i in range(1, N+1):
            self.fact.append((self.fact[-1]*i)%MOD)
            self.fact_inv.append(pow(self.fact[-1], MOD-2, MOD))
    def C(self, N, K):
        if N >= K:
            return self.fact[N]*self.fact_inv[K]%MOD*self.fact_inv[N-K]%MOD
        else:
            return 0
    def P(self, N, K):
        if N >= K:
            return self.fact[N]*self.fact_inv[N-K]%MOD
        else:
            return 0

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

cnt = [0]*3
Q = [0]*3
MOD = 998244353
for i in range(N):
    for j in range(M):
        if S[i][j] == "B":
            cnt[(i+j)%3] += 1
        elif S[i][j] == "?":
            Q[(i+j)%3] += 1

cp = CP(N*M)
odd = 1
for i in range(3):
    o = 0
    if cnt[i]%2 == 0:
        c = 1
        while c <= Q[i]:
            o += cp.C(Q[i], c)
            o %= MOD
            c += 2
    else:
        c = 0
        while c <= Q[i]:
            o += cp.C(Q[i], c)
            o %= MOD
            c += 2
    odd *= o
    odd %= MOD

even = 1
for i in range(3):
    e = 0
    if cnt[i]%2 == 0:
        c = 0
        while c <= Q[i]:
            e += cp.C(Q[i], c)
            e %= MOD
            c += 2
    else:
        c = 1
        while c <= Q[i]:
            e += cp.C(Q[i], c)
            e %= MOD
            c += 2
    even *= e
    even %= MOD

print((odd+even)%MOD)