ABC311F AC

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#ifndef __DEBUG__
#define dbg(...) 42
#endif
template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vl = vector<ll>;
using vi = vector<int>;

constexpr int mod = 998244353;

int main(int argc, char **argv)
{
    int n, m;
    cin >> n >> m;
    vector<string> vs(n);
    for (auto &s : vs)
        cin >> s;

    ll ans = 0;
    auto get_first_row = [&](int col) {
        for (int i = 0; i < n; ++i)
            if (vs[i][col] == '#')
                return i;
        return n;
    };
    vector<int> fbs(m, n);
    for (int i = 0; i < m; ++i)
        fbs[i] = get_first_row(i);

    vector<ll> dp(n + 2, 0);
    for (int i = fbs[0]; i >= 0; --i)
        dp[i] = dp[i + 1] + 1;
    for (int i = 1; i < m; ++i) {
        vector<ll> ndp(n + 2, 0);
        for (int j = fbs[i]; j >= 0; --j)
            ndp[j] = (ndp[j + 1] + (j >= 1 ? dp[j - 1] : dp[0])) % mod;
        dp.swap(ndp);
    }
    cout << dp[0] << endl;
    return 0;
};