#include <stdio.h>

const int Mod = 998244353;
long long fact[250001], fact_inv[250001];

long long div_mod(long long x, long long y, long long z)
{
	if (x % y == 0) return x / y;
	else return (div_mod((1 + x / y) * y - x, (z % y), y) * z + x) / y;
}

long long combination(int n, int k)
{
	if (k < 0 || n < k) return 0;
	return fact[n] * fact_inv[k] % Mod * fact_inv[n-k] % Mod;
}

int main()
{
	int i, N, M;
	char S[501][501];
	scanf("%d %d", &N, &M);
	for (i = 0; i < N; i++) scanf("%s", S[i]);

	for (i = 1, fact[0] = 1; i <= N * M; i++) fact[i] = fact[i-1] * i % Mod;
	for (i = N * M - 1, fact_inv[N*M] = div_mod(1, fact[N*M], Mod); i >= 0; i--) fact_inv[i] = fact_inv[i+1] * (i + 1) % Mod;

	int j, num[2][3] = {};
	for (i = 0; i < N; i++) {
		for (j = 0; j < M; j++) {
			if (S[i][j] == '?') num[1][(i+j)%3]++;
			else if (S[i][j] == 'B') num[0][(i+j)%3]++;
		}
	}
	
	int k;
	long long count[2][3] = {};
	for (i = 0; i <= num[1][0]; i++) count[(num[0][0]+i)%2][0] += combination(num[1][0], i);
	for (i = 0; i <= num[1][1]; i++) count[(num[0][1]+i)%2][1] += combination(num[1][1], i);
	for (i = 0; i <= num[1][2]; i++) count[(num[0][2]+i)%2][2] += combination(num[1][2], i);
	for (i = 0; i < 2; i++) for (j = 0; j < 3; j++) count[i][j] %= Mod;
	printf("%lld\n", (count[0][0] * count[0][1] % Mod * count[0][2] + count[1][0] * count[1][1] % Mod * count[1][2]) % Mod);
	fflush(stdout);
	return 0;
}