#define MD 998244353
ll@H,@W,B[3]{},Q[]{},k;rep(i,H){string@s;rep[s,j](c,W)B[k=(i+j)%3]^=c==66,Q[k]+=c<66;}Mint t=2;wt(sum[d,0,2](mul[i,0,3](Q[i]?t**(Q[i]-1):(B[i]==d)*t/2)));