#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<int>> E(H, vector<int>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      char S;
      cin >> S;
      if (S == '#') E[i][j] = 1;
    }
  }
  bool ikeru = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (E[i][j] == 1) {
        int count = 0;
        if (j - 1 >= 0 && E[i][j - 1] == 1) count++;
        if (j + 1 < W && E[i][j + 1] == 1) count++;
        if (i - 1 >= 0 && E[i - 1][j] == 1) count++;
        if (i < H && E[i + 1][j] == 1) count++;
        if (count == 0) ikeru = false;
      }
    }
  }
  if (ikeru)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
