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