#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  int dx[4] = {-1, 1, 0, 0};
  int dy[4] = {0, 0, -1, 1};
  char board[H][W];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> board[i][j];
    }
  }
  bool ans = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (board[i][j] == '#') {
        bool can2 = false;
        for (int k = 0; k < 4; k++) {
          int nx = i + dx[k];
          int ny = j + dy[k];
          if (nx < 0 || nx >= H) continue;
          if (ny < 0 || ny >= H) continue;
          if (board[nx][ny] == '#') can2 = true;
        }
        if (!can2) ans = false;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
