#include <bits/stdc++.h>
using namespace std;
int main() {
  char math[60][60];
  int H, W;
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> math[i][j];
    }
  }
  int s_check = 0;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      char temp = math[i][j];
      if (temp == '#') {
        int check = 0;
        if ((j + 1) < W) {
          if (temp != math[i][j + 1]) check++;
        } else
          check++;
        if ((i + 1) < H) {
          if (temp != math[i + 1][j]) check++;
        } else
          check++;
        if ((i - 1) > 0) {
          if (temp != math[i - 1][j]) check++;
        } else
          check++;
        if ((j - 1) > 0) {
          if (temp != math[i][j - 1]) check++;
        } else
          check++;
        if (check == 4) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
