#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> s(H, vector<char>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        int cnt = 0;
        for (int x = 0; x < 4; x++) {
          if (s[i + dx[x]][j + dy[x]] == '#') cnt++;
        }
        if (cnt == 0) {
          cout << "No" << endl;
        }
      }
    }
  }
  cout << "Yes" << endl;
}
