#include <bits/stdc++.h>
using namespace std;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define Return(ans) { cout << (ans) << endl; return 0; }
#define pb push_back
#define fi first
#define se second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void Ans(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

//const int mod = 1000000007;
const int mod = 998244353;

template<long long MOD>
struct ModInt{

    using ll = long long;
    ll val;

    void setval(ll v) { val = v % MOD; };
    ModInt(): val(0) {}
    ModInt(ll v) { setval(v); };

    ModInt operator+(const ModInt &x) const { return ModInt(val + x.val); }
    ModInt operator-(const ModInt &x) const { return ModInt(val - x.val + MOD); }
    ModInt operator*(const ModInt &x) const { return ModInt(val * x.val); }
    ModInt operator/(const ModInt &x) const { return *this * x.inv(); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt operator+=(const ModInt &x) { return *this = *this + x; }
    ModInt operator-=(const ModInt &x) { return *this = *this - x; }
    ModInt operator*=(const ModInt &x) { return *this = *this * x; }
    ModInt operator/=(const ModInt &x) { return *this = *this / x; }

    friend ostream& operator<<(ostream &os, const ModInt &x) { os << x.val; return os; }
    friend istream& operator>>(istream &is, ModInt &x) { is >> x.val; x.val = (x.val % MOD + MOD) % MOD; return is; }

    ModInt pow(ll n) const {
        ModInt a = 1;
        if(n == 0) return a;
        int i0 = 64 - __builtin_clzll(n);
        for(int i = i0 - 1; i >= 0; i--){
            a = a * a;
            if((n >> i) & 1) a *= (*this); 
        }
        return a;
    }
    ModInt inv() const { return this->pow(MOD - 2); }
};

using mint = ModInt<mod>; mint pow(mint x, long long n) { return x.pow(n); }
//using mint = double; //for debug
using mvec = vector<mint>;
using mmat = vector<mvec>;

struct Combination{

    vector<mint> fact, invfact;

    Combination(int N){
        fact = vector<mint>({mint(1)});
        invfact = vector<mint>({mint(1)});
        fact_initialize(N);
    }

    void fact_initialize(int N){
        int i0 = fact.size();
        if(i0 >= N + 1) return;
        fact.resize(N + 1);
        invfact.resize(N + 1);
        for(int i = i0; i <= N; i++) fact[i] = fact[i - 1] * i;
        invfact[N] = (mint)1 / fact[N];
        for(int i = N - 1; i >= i0; i--) invfact[i] = invfact[i + 1] * (i + 1); 
    }

    mint nCr(int n, int r){
        if(n < 0 || r < 0 || r > n) return mint(0);
        if(fact.size() < n + 1) fact_initialize(n);
        return fact[n] * invfact[r] * invfact[n - r];
    }

    mint nPr(int n, int r){
        if(n < 0 || r < 0 || r > n) return mint(0);
        if(fact.size() < n + 1) fact_initialize(n);
        return fact[n] * invfact[n - r];
    }

    mint Catalan(int n){
        if(n < 0) return 0;
        else if(n == 0) return 1;
        if(fact.size() < 2 * n + 1) fact_initialize(2 * n);
        return fact[2 * n] * invfact[n + 1] * invfact[n];
    }

};

signed main(){

    int H, W; cin >> H >> W;
    vector<string> A(H); cin >> A;

    int n = H + W;
    Combination C(n);
    mmat sti(n + 1);
    sti[0] = mvec(1, 1);
    FOR(i, 1, n + 1){
        sti[i].resize(i + 1);
        sti[i][0] = 0;
        FOR(j, 1, i) sti[i][j] = sti[i - 1][j - 1] + sti[i - 1][j] * j;
        sti[i][i] = 1;
    }

    mmat dp(H + 1, mvec(W, 0));
    dp[0][0] = 1;
    REP(i, H){
        REP(j, W){
            dp[i + 1][j] += dp[i][j] * (j + 2);
            if(j < W - 1) dp[i + 1][j + 1] += dp[i][j];
        }
    }
    
    mmat dq(H + 1, mvec(W + 1, 0));
    REP(h, H + 1) REP(w, W + 1){
        REP(k, w) dq[h][w] += dp[h][k] * sti[w][k + 1] * C.fact[k + 1] * C.fact[k];
        if(w == 0) dq[h][w] = 1;
    }

    mmat dq2(H + 1, mvec(W + 1, 0));
    REP(h, H + 1) REP(w, W + 1){
        REP(i, h + 1) REP(j, w + 1){
            dq2[h][w] += dq[i][w - j] * dq[h - i][j] * C.nCr(h, i) * C.nCr(w, j);
        }
    }
    
    mint ans = dq[H][W];

    mat flgx(bit(H), vec(W, 0)), flgy(bit(W), vec(H, 0));
    REP(x, bit(H)){
        REP(j1, W) REP(j2, j1){
            bool f = false;
            
            REP(i1, H) REP(i2, i1) if((x >> i1) & (x >> i2) & 1){
                if(A[i1][j1] == A[i2][j2] && A[i1][j2] == A[i2][j1] && A[i1][j1] != A[i2][j1]){
                    f = true;
                }
            }
            if(f){
                flgx[x][j1] ^= bit(j2);
                flgx[x][j2] ^= bit(j1);
            }
        }
    }

    REP(y, bit(W)){
        REP(i1, H) REP(i2, i1){
            bool f = false;

            REP(j1, W) REP(j2, j1) if((y >> j1) & (y >> j2) & 1){
                if(A[i1][j1] == A[i2][j2] && A[i1][j2] == A[i2][j1] && A[i1][j1] != A[i2][j1]){
                    f = true;
                }
            }
            if(f){
                flgy[y][i1] ^= bit(i2);
                flgy[y][i2] ^= bit(i1);
            }
        }
    }

    vector<v_bool> difx(bit(H), v_bool(W, false)), dify(bit(W), v_bool(H, false));
    REP(x, bit(H)) REP(j, W){
        REP(i1, H) REP(i2, i1) if((x >> i1) & (x >> i2) & 1){
            if(A[i1][j] != A[i2][j]) difx[x][j] = true;
        }
    }
    REP(y, bit(W)) REP(i, H){
        REP(j1, W) REP(j2, j1) if((y >> j1) & (y >> j2) & 1){
            if(A[i][j1] != A[i][j2]) dify[y][i] = true;
        }
    }

    REP(x, bit(H)) REP(y, bit(W)){
        int tx = 0;
        REP(i, H) if((x >> i) & 1) tx |= flgy[y][i];
        int ty = 0;
        REP(j, W) if((y >> j) & 1) ty |= flgx[x][j];

        bool f = true;
        int ux = x ^ (x & tx), uy = y ^ (y & ty);
        REP(i, H) if(((ux >> i) & 1) && !dify[y & ty][i]) f = false;
        REP(j, W) if(((uy >> j) & 1) && !difx[x & tx][j]) f = false;

        if(f){
            int h = H - __builtin_popcountll(x), w = W - __builtin_popcountll(y);
            if(h < H && w < W) ans += dq2[h][w];
        }
    }

    Out(ans);

    return 0;
}


Measured memory_bytes: 640