import sys
input = sys.stdin.readline

mod=998244353

FACT=[1]
for i in range(1,2*10**6+1):
    FACT.append(FACT[-1]*i%mod)

FACT_INV=[pow(FACT[-1],mod-2,mod)]
for i in range(2*10**6,0,-1):
    FACT_INV.append(FACT_INV[-1]*i%mod)

FACT_INV.reverse()

def Combi(a,b):
    if 0<=b<=a:
        return FACT[a]*FACT_INV[b]%mod*FACT_INV[a-b]%mod
    else:
        return 0

N,M=map(int,input().split())

MAP=[input().strip() for i in range(N)]

B=[0,0,0]
Q=[0,0,0]

for i in range(N):
    for j in range(M):
        if MAP[i][j]=="B":
            B[(j+i)%3]+=1
        if MAP[i][j]=="?":
            Q[(j+i)%3]+=1

for i in range(3):
    B[i]%=2

ANS1=1
for i in range(3):
    score=[0,0,0]
    for j in range(3):    
        for k in range(Q[j]+1):
            if k%2==B[j]%2:
                score[j]=score[j]+Combi(Q[j],k)
                score[j]%=mod

    ANS1=score[0]*score[1]*score[2]

for i in range(3):
    B[i]+=1

ANS2=1
for i in range(3):
    score=[0,0,0]
    for j in range(3):    
        for k in range(Q[j]+1):
            if k%2==B[j]%2:
                score[j]=score[j]+Combi(Q[j],k)
                score[j]%=mod

    ANS2=score[0]*score[1]*score[2]

print((ANS1+ANS2)%mod)