#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, -1, 0, 1};
  bool isPossible;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        isPossible = false;
        for (int k = 0; k < 4; k++) {
          int x = j + dx[k];
          int y = i + dy[k];
          if (x < 0 || w <= x)
            continue;
          else if (y < 0 || h <= y)
            continue;
          if (s[x][y] == '#') {
            isPossible = true;
          }
        }
        if (isPossible == false) break;
      }
      if (isPossible == false) break;
    }
    if (isPossible == false) break;
  }
  cout << (isPossible ? "Yes" : "No") << endl;
  return 0;
}
