#include <iostream>
using namespace std;

int main() {
  int h, w;
  cin >> h >> w;
  char m[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> m[i][j];
    }
  }

  bool a = true;

  for (int i = 0; i < h - 1; i++) {
    for (int j = 0; j < w - 1; j++) {
      if (m[i][j] == '#') {
        if (m[i + 1] != '#' && m[i + 1] != '#') a = false;
      }
    }
  }

  if (a) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  
	return 0;
}