#include <atcoder/all>
#include <bits/stdc++.h>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
using namespace atcoder;
using namespace std;

using mint = modint998244353;

typedef long long ll;

struct Comb {
    vector<mint> fact, ifact;
    int MAX_COM;
    Comb() {}
    Comb(int n) {
        MAX_COM = n; // ここでMAX入力を調整
        init(998244353, MAX_COM);
    }
    void init(long long MOD, long long MAX_COM) {
        int n = MAX_COM;
        assert(n < MOD);
        fact = vector<mint>(n + 1);
        ifact = vector<mint>(n + 1);
        fact[0] = 1;
        for (int i = 1; i <= n; ++i)
            fact[i] = fact[i - 1] * i;
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; --i)
            ifact[i - 1] = ifact[i] * i;
    }
    mint operator()(long long n, long long k) {
        if (k < 0 || k > n)
            return 0;
        return fact[n] * ifact[k] * ifact[n - k];
    }
};
Comb comb(5000010);

mint f(int bl, int qu, int p) {
    cerr << bl << " " << qu << endl;
    mint res = 0;
    rep(i, 0, qu + 1) {
        if ((bl + i) % 2 == p) {
            res += comb(qu, i);
        }
    }
    return res;
}

int main() {
    int h, w;
    cin >> h >> w;
    vector<string> s(h);
    rep(i, 0, h) cin >> s[i];
    vector<int> bl(3), qu(3);
    rep(i, 0, h) rep(j, 0, w) {
        if (s[i][j] == 'B') {
            bl[(i + j) % 3]++;
        } else if (s[i][j] == '?') {
            qu[(i + j) % 3]++;
        }
    }
    mint ans1 = 1, ans2 = 1;
    rep(i, 0, 3) {
        ans1 *= f(bl[i], qu[i], 0);
        ans2 *= f(bl[i], qu[i], 1);
    }
    mint ans = ans1 + ans2;
    cout << ans.val() << endl;
}