// 

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

using ll = long long;

#define rep(i, n) for (int i=0; i<(int)(n); ++(i))
#define rep3(i, m, n) for (int i=(m); (i)<(int)(n); ++(i))
#define repr(i, n) for (int i=(int)(n)-1; (i)>=0; --(i))
#define rep3r(i, m, n) for (int i=(int)(n)-1; (i)>=(int)(m); --(i))
#define all(x) (x).begin(), (x).end()

using mint = modint998244353;
const int INF = (int)(1e9);
const ll mod = 998244353LL;

int main() {
    int n, m;
    cin >> n >> m;
    vector<string> s(n);
    rep(i, n) cin >> s[i];
    vector<int> bcnt(3), qcnt(3);
    rep(i, n) rep(j, m) {
        if (s[i][j] == 'B') bcnt[(i+j)%3]++;
        else if (s[i][j] == '?') qcnt[(i+j)%3]++;
    }
    int ri = -1;
    bool ok = true;
    rep(i, 3) if (qcnt[i] == 0) {
        if (ri == -1) ri = bcnt[i] % 2;
        else if (ri != bcnt[i] % 2) ok = false;
    }
    if (!ok) {
        cout << 0 << endl;
        return 0;
    }
    mint res = 1;
    rep(i, 3) if (qcnt[i] > 0) res *= mint(2).pow(qcnt[i]-1);
    if (ri == -1) res *= 2;
    cout << res.val() << endl;
    return 0;
}