#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string s[60];
  int x[4] = {0, 1, 0, -1};
  int y[4] = {1, 0, -1, 0};
  cin >> h >> w;
  for (int i = 0; i < h; i++) cin >> s[i];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      bool find = true;
      if (s[i][j] == '.') continue;
      for (int k = 0; k < 4; k++) {
        int dx = i + x[k];
        int dy = j + y[k];
        if (dx < 0 || dy < 0 || w <= dx || h <= dy) continue;
        if (s[dx][dy] == '#') find = false;
      }
      if (find) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
}
