#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

using Mint = atcoder::modint998244353;

void Solve() {
  int h, w;
  IN(h, w);
  vector<string> s(h);
  IN(s);
  int mask = 0;
  array<int, 3> c{};
  for (int i : Rep(h)) {
    for (int j : Rep(w)) {
      int r = (i + j) % 3;
      if (s[i][j] == 'W') {
      } else if (s[i][j] == 'B') {
        mask ^= 1 << r;
      } else {
        ++c[r];
      }
    }
  }
  Mint ans = 0;
  for (int p : Rep(2)) {
    Mint cur = 1;
    for (int r : Rep(3)) {
      if ((mask >> r & 1) == p) {
        cur *= c[r] == 0 ? 1 : Mint(2).pow(c[r] - 1);
      } else {
        cur *= c[r] == 0 ? 0 : Mint(2).pow(c[r] - 1);
      }
    }
    ans += cur;
  }
  OUT(ans);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  Solve();
}

#elif __INCLUDE_LEVEL__ == 1

#include <bits/stdc++.h>

#include <atcoder/modint>

template <class T> concept Range = std::ranges::range<T> && !std::convertible_to<T, std::string_view>;
template <class T> concept Tuple = std::__is_tuple_like<T>::value && !Range<T>;

namespace std {

istream& operator>>(istream& is, Range auto&& r) {
  for (auto&& e : r) {
    is >> e;
  }
  return is;
}

istream& operator>>(istream& is, Tuple auto&& t) {
  return apply([&](auto&... xs) -> istream& { return (is >> ... >> xs); }, t);
}

ostream& operator<<(ostream& os, Range auto&& r) {
  for (string_view sep = ""; auto&& e : r) {
    os << exchange(sep, " ") << e;
  }
  return os;
}

ostream& operator<<(ostream& os, Tuple auto&& t) {
  return apply([&](auto&... xs) -> ostream& {
    [[maybe_unused]] string_view sep = "";
    ((os << exchange(sep, " ") << xs), ...);
    return os; }, t);
}

template <class T, atcoder::internal::is_modint_t<T>* = nullptr>
istream& operator>>(istream& is, T& x) {
  int v;
  is >> v;
  x = T::raw(v);
  return is;
}

template <class T, atcoder::internal::is_modint_t<T>* = nullptr>
ostream& operator<<(ostream& os, const T& x) {
  return os << x.val();
}

}  // namespace std

#define DEF_INC_OR_DEC(op) \
  auto& operator op(Tuple auto&&); \
  auto& operator op(Range auto&& r) { \
    for (auto&& e : r) { \
      op e; \
    } \
    return r; \
  } \
  auto& operator op(Tuple auto&& t) { \
    std::apply([](auto&... xs) { (op xs, ...); }, t); \
    return t; \
  }

DEF_INC_OR_DEC(++)
DEF_INC_OR_DEC(--)

#undef DEF_INC_OR_DEC

#define IN(...) cin >> forward_as_tuple(__VA_ARGS__)
#define OUT(...) cout << forward_as_tuple(__VA_ARGS__) << '\n'

using namespace std;

using views::filter, views::transform, views::take, views::drop;

constexpr auto Rev = views::reverse;

constexpr auto Rep(int l, int r) { return views::iota(min(l, r), r); }
constexpr auto Rep(int n) { return Rep(0, n); }
constexpr auto Rep1(int l, int r) { return Rep(l, r + 1); }
constexpr auto Rep1(int n) { return Rep(1, n + 1); }

constexpr auto DivFloor(auto x, auto y) { return x / y - ((x ^ y) < 0 && x % y != 0); }
constexpr auto DivCeil(auto x, auto y) { return x / y + (0 <= (x ^ y) && x % y != 0); }
constexpr auto Floor(auto x, auto y) { return DivFloor(x, y) * y; }
constexpr auto Floor(auto x, auto y, auto z) { return Floor(x - z, y) + z; }
constexpr auto Ceil(auto x, auto y) { return DivCeil(x, y) * y; }
constexpr auto Ceil(auto x, auto y, auto z) { return Ceil(x - z, y) + z; }
constexpr auto Mod(auto x, auto y) { return x - Floor(x, y); }

template <class T, class U = T> bool SetMin(T& x, U&& y) { return y < x && (x = forward<U>(y), true); }
template <class T, class U = T> bool SetMax(T& x, U&& y) { return x < y && (x = forward<U>(y), true); }

constexpr int INF = INT_MAX / 2;
constexpr int64_t INF64 = INT64_MAX / 2;

#endif  // __INCLUDE_LEVEL__ == 1