#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H;
  int W;
  int result = 0;
  vector<string> maps(50);
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    cin >> maps[i];
  }
  for (int i = 0; i < H; i++) {
    result = 1;
    for (int j = 0; j < W; j++) {
      if (maps[i][j] == '#') {
        if ((j + 1) < W && maps[i][j + 1] == '#') result = 0;
        if ((j - 1) >= 0 && maps[i][j - 1] == '#') result = 0;
        if ((i + 1) < H && maps[i + 1][j] == '#') result = 0;
        if ((i - 1) >= 0 && maps[i - 1][j] == '#') result = 0;
        if (result == 1) break;
      }
    }
  }
  if (result == 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
