n,m = map(int,input().split())
s = [input() for _ in range(n)]
nmax = n*m; mod = 998244353; fa = [1]*(nmax+1); fi = [1]*(nmax+1)
for i in range(1,nmax): fa[i+1] = fa[i]*(i+1)%mod
fi[nmax] = pow(fa[nmax],mod-2,mod)
for i in range(nmax,0,-1): fi[i-1] = fi[i]*i%mod
def cmb(n,r): return fa[n]*fi[n-r]%mod*fi[r]%mod if 0<=r<=n else 0
a = [0]*3; b = [0]*3; c = [0]*3; d = [0]*3
for i in range(n):
    for j in range(m):
        if s[i][j]=="B": a[(i+j)%3] += 1
        if s[i][j]=="?": b[(i+j)%3] += 1
for i,v in enumerate(b):
    for j in range(v+1):
        if (a[i]+j)%2: c[i] += cmb(v,j)
        else: d[i] += cmb(v,j)
print((c[0]*c[1]*c[2]+d[0]*d[1]*d[2])%mod)