#include <bits/stdc++.h>
using namespace std;
#include<atcoder/modint>
using namespace atcoder;
using ll = long long;
const ll mod=998244353;

using mint=modint998244353;

using vm = vector<mint>;
using vvm = vector<vm>;
using vvvm = vector<vvm>;


vector<mint> fact, factinv, inv, factK;
void prenCkModp(ll n) {
    // factK.resize(4*n+5);
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact[0] = fact[1] = 1;
    factinv[0] = factinv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact[i] = (fact[i - 1] * i);
        inv[i] = (mod - ((inv[mod % i] * (mod / i))));
        factinv[i] = (factinv[i - 1] * inv[i]);
    }
}
mint nCk(ll n, ll k) {
    if (n < k || k < 0) return 0;
    return (fact[n] * ((factinv[k] * factinv[n - k])));
}

int main() {
    ll N,M;
    cin>>N>>M;
    vector<string> S(N);
    vector<ll> B(3,0),P(3,0);
    for(int i=0;i<N;i++){
        string S;
        cin>>S;
        for(int j=0;j<M;j++){
            if(S[j]=='B')B[(i+j)%3]++;
            if(S[j]=='?')P[(i+j)%3]++;
        }
    }
    mint an=0;
    prenCkModp(N*M+1);
    vector<mint> O(3,0),E(3,0);
    for(int i=0;i<3;i++){
        if(P[i]==0){
            O[i]=1;
            E[i]=0;
        }
        else{
            O[i]=E[i]=mint(2).pow(P[i]-1);
        }
    }
    // for(int i=0;i<3;i++)cout<<B[i]<<" "<<O[i].val()<<" "<<E[i].val()<<endl;
    for(int i=0;i<2;i++){
        mint res=1;
        for(int j=0;j<3;j++){
            if(B[j]%2==i){
                res*=E[j];
            }
            else res*=O[j];
        }
        an+=res;
    }
    cout<<an.val()<<endl;


}