#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
int main() {
  int h, w;
  cin >> h >> w;
  string board[h];
  for (int i = 0; i < (h); ++i) cin >> board[i];
  int dy[4] = {1, 0, -1, 0};
  int dx[4] = {0, 1, 0, -1};
  vector<vector<bool>> check(h, vector<bool>(w, false));
  for (int i = 0; i < (h); ++i) {
    for (int j = 0; j < (w); ++j) {
      if (board[i][j] == '#') {
        for (int k = 0; k < (4); ++k) {
          int y = j + dy[k];
          int x = i + dx[k];
          if (x < 0 || x >= w || y < 0 || y >= h) continue;
          if (board[x][y] == '#') check[i][j] = true;
        }
      }
    }
  }
  bool ok = true;
  for (int i = 0; i < (h); ++i) {
    for (int j = 0; j < (w); ++j) {
      if (board[i][j] == '#' && check[i][j] == false) ok = false;
    }
  }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
