#ifdef NACHIA
#define _GLIBCXX_DEBUG
#else
#define NDEBUG
#endif
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using i64 = long long;
using u64 = unsigned long long;
#define rep(i,n) for(int i=0; i<int(n); i++)
const i64 INF = 1001001001001001001;
template<typename A> void chmin(A& l, const A& r){ if(r < l) l = r; }
template<typename A> void chmax(A& l, const A& r){ if(l < r) l = r; }
#include <atcoder/modint>
#include <atcoder/dsu>
using Modint = atcoder::static_modint<998244353>;
using namespace std;

void testcase(){
    int H, W; cin >> H >> W;
    vector<string> A(H);
    rep(y,H) cin >> A[y];
    int k[3] = {};
    int s[3] = {};
    rep(y,H) rep(x,W){
        int q = (y+x)%3;
        if(A[y][x] == '?') k[q]++;
        if(A[y][x] == 'B') s[q] ^= 1;
    }
    Modint ans = 1;
    int q = -1;
    rep(t,3){
        if(k[t] == 0){
            if(q != -1 && q != s[t]) ans = 0;
            q = s[t];
        }
        else ans *= Modint(2).pow(k[t]-1);
    }
    cout << ans.val() << endl;
}

int main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    testcase();
    return 0;
}