#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int H, W;
  cin >> H >> W;
  static bool bord[100][100] = {0};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      char s;
      cin >> s;
      if (s == '#') bord[i + 1][j + 1] = 1;
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (!(bord[i + 1][i + 1])) continue;
      if (bord[i][i + 1]) continue;
      if (bord[i + 1][i]) continue;
      if (bord[i + 2][i + 1]) continue;
      if (bord[i + 1][i + 2]) continue;
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
}
