#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> board(H + 2, vector<char>(W + 2, 'x'));
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      char a;
      cin >> a;
      board[i][j] = a;
    }
  }
  string ans = "No";
  bool finish = false;
  int dy[4] = {-1, 0, 1, 0}, dx[4] = {0, 1, 0, -1};
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (board[i][j] == '.') continue;
      for (int k = 0; k < 4; k++) {
        int y = dy[k], x = dx[k];
        if (board[i + y][j + x] == '#') break;
        if (k == 3) finish = true;
      }
    }
    if (finish) break;
    if (i == H) ans = "Yes";
  }
  cout << ans << endl;
}
