#include <bits/stdc++.h>
using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;
using pii = pair<int, int>;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> s(H, vector<char>(W));
  for (int i = 0; i < (int)(H); i++) {
    for (int j = 0; j < (int)(W); j++) {
      cin >> s[i][j];
    }
  }
  vector<int> dy = {-1, 1, 0, 0};
  vector<int> dx = {0, 0, -1, 1};
  bool check = false;
  for (int i = 0; i < (int)(H); i++) {
    for (int j = 0; j < (int)(W); j++) {
      if (s[i][j] == '.') continue;
      for (int k = 0; k < (int)(4); k++) {
        if (i + dy[k] < 0 || i + dy[k] >= H || j + dx[k] < 0 || j + dx[k] >= W)
          continue;
        if (s[i + dy[k]][j + dx[k]] == '#') {
          check = true;
          break;
        }
      }
      if (!check) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
