//code by p1ckle/sft
#include <bits/stdc++.h>
#define int long long int
#define pii pair<int, int>
#define F first
#define S second
#define mid ((start+end)/2)
#define all(x) x.begin(), x.end()
#define ub(a, b) upper_bound(all(a), b)
#define lb(a, b) lower_bound(all(a), b)
#define pb(a) push_back(a)

using namespace std;

const int inf = 1e18, mod = 998244353;
int max (vector<int> a) {int t = -inf; for (int i : a) t = max(t, i); return t;}

int n, m, q[3], b[3], ans;
string s[505];
bool o, e;

int sq(int a) {
	
    int res = 1, p = 2;
	while (a > 0) {

		if (a & 1) res = (res*p)%mod;
		p = (p*p)%mod;
		a >>= 1;

	}
	return res;

}

signed main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> n >> m;
    for (int i = 0; i < n; i++) cin >> s[i];
    for (int i = 0; i < n; i++) {

        for (int j = 0; j < m; j++) {

            if (s[i][j] == 'B') b[(i+j)%3]++;
            else if (s[i][j] == '?') q[(i+j)%3]++;

        }

    }

    for (int i = 0; i < 3; i++) if (b[i]%2 == 0 && !q[i]) o = true;
    if (!o) {

        ans += (((sq(q[0]-1)*sq(q[1]-1))%mod)*sq(q[2]-1))%mod;

    }
    for (int i = 0; i < 3; i++) if (b[i]%2 == 1 && !q[i]) e = true;
    if (!e) {

        ans += (((sq(q[0]-1)*sq(q[1]-1))%mod)*sq(q[2]-1))%mod;

    }
    cout << ans%mod;

}