#include <iostream>
#include <string>
#include <vector>
#include <atcoder/modint>

using namespace std;
using namespace atcoder;
using mint = modint998244353;
string s[510];
mint dp[4][2][2][2];
mint pw(mint a,int x){
    mint ret = 1;
    while(x){
        if(x&1) (ret *= a);
        (a *= a); x /= 2;
    }
    return ret;
}

int main(){
    int i,j,n,m; cin >> n >> m;
    for(i=0;i<n;i++) cin >> s[i];
    int r,g,b,R,G,B;
    r = g = b = 0;
    R = G = B = 0;
    for(i=0;i<n;i++){
        for(j=0;j<m;j++){
            int k = (i + j)%3;
            if(s[i][j]=='?'){
                if(k==0) R++;
                else if(k==1) G++;
                else B++;
            }
            if(s[i][j]=='B'){
                if(k==0) r++;
                else if(k==1) g++;
                else b++;
            }
        }
    }
    dp[0][r&1][g&1][b&1] = 1;
    vector<int> v = {R,G,B};
    for(int id=0;id<3;id++){
        for(i=0;i<2;i++){
            for(j=0;j<2;j++){
                for(int k=0;k<2;k++){
                    if(v[id]==0){
                        dp[id + 1][i][j][k] = dp[id][i][j][k];
                    }else{
                        dp[id + 1][i][j][k] += pw(2,v[id] - 1)*dp[id][i][j][k];
                        if(id==0){
                            dp[id + 1][i^1][j][k] += pw(2,v[id] - 1)*dp[id][i][j][k];
                        }
                        if(id==1){
                            dp[id + 1][i][j^1][k] += pw(2,v[id] - 1)*dp[id][i][j][k];
                        }
                        if(id==2){
                            dp[id + 1][i][j][k^1] += pw(2,v[id] - 1)*dp[id][i][j][k];
                        }
                    }
                }
            }
        }
    }
    mint ans = dp[3][0][0][0] + dp[3][1][1][1];
    cout << ans.val() << "\n";
}