#include <bits/stdc++.h>
using namespace std;
int main() {
  char map[50][50];
  int h, w;
  int count = 0;
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> map[i][j];
    }
  }
  bool a = false;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (map[i][j] == '#') {
        count++;
        if (i - 1 != 0 && map[i - 1][j] == '#') {
          a = true;
          continue;
        } else if (i + 1 != h && map[i + 1][j] == '#') {
          a = true;
          continue;
        } else if (j - 1 != -1 && map[i][j - 1] == '#') {
          a = true;
          continue;
        } else if (j + 1 != w && map[i][j + 1] == '#') {
          a = true;
          continue;
        } else {
          goto end;
        }
      }
    }
  }
end:
  if (a || count == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
