#include <bits/stdc++.h>
using namespace std;
char grid[50][50];
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  char grid[50][50];
  int h;
  int w;
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> grid[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (grid[i][j] == '#' &&
          (grid[i - 1][j] == '#' || grid[i + 1][j] == '#' ||
           grid[i][j - 1] == '#' || grid[i][j + 1] == '#') == false) {
        cout << grid[i][j] << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
