#include <bits/stdc++.h>
using namespace std;
vector<int> dx = {-1, 0, 0, 1};
vector<int> dy = {0, -1, 1, 0};
void solve() {
  int H, W;
  cin >> H >> W;
  vector<string> canvas(H);
  for (int h = 0; h < H; h++) cin >> canvas[h];
  bool ok = true;
  int nx, ny;
  for (int h = 0; h < H; h++)
    for (int w = 0; w < W; w++) {
      if (canvas[h][w] != '#') continue;
      int cnt = 0;
      for (int i = 0; i < 4; i++) {
        ny = h + dy[i];
        nx = w + dx[i];
        if (ny >= H || 0 > ny || nx >= W || 0 > nx) continue;
        if (canvas[ny][nx] != '#') cnt++;
        if (cnt == 4) ok = false;
        break;
      }
    }
  cout << (ok ? "Yes" : "No") << endl;
}
int main(void) {
  solve();
  return 0;
}
