#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001


int main(){
	
	int h,w;
	cin>>h>>w;
	
	vector<string> s(h);
	rep(i,h)cin>>s[i];
	
	rep(i,h){
		rep(j,w){
			if(s[i][j]=='?'){
				
			}
			else if(s[i][j]=='B')s[i][j] = '1';
			else s[i][j] = '0';
		}
	}
	vector<mint> dp(1<<3,0);
	dp[0] = 1;
	rep(i,h){
		
		rep(j,w){
			vector<mint> ndp(8,0);
			rep(k,2){
				if(s[i][j]=='?'||s[i][j]==k+'0'){
					rep(l,8){
						int nl = l;
						nl ^= k << (((i+j)%3+3)%3);
						ndp[nl] += dp[l];
					}
					
				}
			}
			swap(dp,ndp);
		}
		
	}

	
	cout<<(dp[0]+dp[7]).val()<<endl;
    return 0;
}