MOD  = 998244353i64
FACT = [1i64]
100000.times do |i|
  FACT << FACT[i] * (i + 1) % MOD
end
FACT_INV = Array.new(FACT.size, 0i64)
FACT_INV[-1] = inv(FACT[-1])
(FACT_INV.size - 2).downto(0) do |i|
  FACT_INV[i] = FACT_INV[i + 1] * (i + 1) % MOD
end

def binom(n, k)
  FACT[n] * FACT_INV[k] % MOD * FACT_INV[n - k] % MOD
end

def inv(v : Int64)
  pow(v, MOD - 2)
end

def pow(v : Int64, p)
  ret = 1i64
  while p > 0
    if (p & 1i64) != 0
      ret *= v
      ret %= MOD
    end
    v *= v
    v %= MOD
    p >>= 1
  end
  ret
end

n, m = read_line.split.map(&.to_i)
s = Array.new(n) { read_line.chars }
cnt_b = Array.new(3, 0)
cnt_q = Array.new(3, 0)
n.times do |i|
  m.times do |j|
    if s[i][j] == 'B'
      cnt_b[(i + j) % 3] += 1
    elsif s[i][j] == '?'
      cnt_q[(i + j) % 3] += 1
    end
  end
end
ans_e = 1i64
ans_o = 1i64
3.times do |i|
  sum_e = 0i64
  sum_o = 0i64
  0.upto(cnt_q[i]) do |j|
    if j % 2 == cnt_b[i] % 2
      sum_e += binom(cnt_q[i], j)
      sum_e %= MOD
    else
      sum_o += binom(cnt_q[i], j)
      sum_o %= MOD
    end
  end
  ans_e *= sum_e
  ans_e % MOD
  ans_o *= sum_o
  ans_o % MOD
end
puts (ans_e + ans_o) % MOD