#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  int i;
  for (i = 0; i < H; i++) cin >> s.at(i);
  vector<int> dx = {-1, 0, 1, 0};
  vector<int> dy = {0, 1, 0, -1};
  bool ans = 0;
  for (i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s.at(i).at(j) == '.') continue;
      int count = 0;
      for (int k = 0; k < 4; k++) {
        int nx = i + dx.at(k);
        int ny = j + dy.at(k);
        if (nx < 0 || nx > H - 1 || ny < 0 || ny > W - 1) continue;
        if (s.at(nx).at(ny) == '#') ans = 1;
      }
      if (ans == 0) break;
    }
    if (ans == 0) {
      cout << "No" << endl;
      break;
    }
  }
  if (ans == 1) cout << "Yes" << endl;
}
