#include <bits/stdc++.h>
using namespace std;
const int maxv = 1e5;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for (int(i) = 0; (i) < (H); i++) cin >> s[i];
  string ans = "Yes";
  int count;
  for (int(i) = 0; (i) < (H); i++) {
    for (int(j) = 0; (j) < (W); j++) {
      if (s[i][j] == '#') {
        count = 0;
        if (i - 1 >= 0 && s[i - 1][j] == '.') count++;
        if (i + 1 < H && s[i + 1][j] == '.') count++;
        if (j - 1 >= 0 && s[i][j - 1] == '.') count++;
        if (j + 1 < W && s[i][j + 1] == '.') count++;
        if (count == 4) ans = "No";
        break;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
