#include <bits/stdc++.h>
using namespace std;
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
int main() {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  int n, m;
  cin >> n >> m;
  vector<string> g(n);
  for (int i = 0; i < n; i++) cin >> g[i];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (g[i][j] != '#') continue;
      bool ok = false;
      for (int k = 0; k < 4; k++) {
        int pair<int, int> = i + dx[k], jj = j + dy[k];
        if (pair<int, int> < 0 || pair<int, int> >= n || jj < 0 || jj >= n)
          continue;
        if (g[pair<int, int>][jj] == '#') ok = true;
      }
      if (!ok) {
        cout << "No\n";
        return 0;
      }
    }
  }
  cout << "Yes\n";
  return 0;
}
