#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];
  }
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, -1, 0, 1};
  bool can = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      bool found = false;
      for (int k = 0; k < 4; k++) {
        int x = i + dx[k];
        int y = j + dy[k];
        if (0 <= x && x < H && 0 <= y && y < W && s[x][y] == '#') found = true;
      }
      if (!found) {
        can = false;
        break;
      }
    }
    if (!can) break;
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
