#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
int N,M;
vector<string> S;
using mint = modint998244353;

void solve(){
    vector<int> Black(3,0);
    vector<int> Gray(3,0);
    for(int i = 0;i<N;i++){
        for(int j = 0;j<M;j++){
            if(S[i][j]=='B'){
                Black[(i+j)%3]++;
            }else if(S[i][j]=='?'){
                Gray[(i+j)%3]++;
            }
        }
    }
    mint ans = 0;
    mint tmp = 1;

    //odd
    for(int i = 0;i<3;i++){
        if(Gray[i]==0){
            if(Black[i]%2==0){
                tmp = 0;
            }
        }else{
            tmp *= mint(2).pow(Gray[i]-1);
        }
    }
    ans += tmp;
    tmp =  1;
    //even
    for(int i = 0;i<3;i++){
        if(Gray[i]==0){
            if(Black[i]%2==1){
                tmp = 0;
            }
        }else{
            tmp *= mint(2).pow(Gray[i]-1);
        }
    }
    ans += tmp;
    cout<<ans.val()<<endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> N >> M;
    S = vector<string>(N);
    for(int i = 0; i < N; i++) cin >> S[i];
    solve();
}