#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  bool flag = false;
  int cnt = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        if (s[i + 1][j] == '#') {
          flag = true;
        }
        if (s[i - 1][j] == '#') {
          flag = true;
        }
        if (s[i][j + 1] == '#') {
          flag = true;
        }
        if (s[i][j - 1] == '#') {
          flag = true;
        }
      } else {
        cnt++;
      }
    }
  }
  if (1 == w * h) {
    if (s[0][0] == '#') {
      cout << "Yes" << endl;
    } else {
      cout << "No" << endl;
    }
  }
  if (cnt == w * h) {
    cout << "Yes" << endl;
    return 0;
  }
  if (flag) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
