#include <bits/stdc++.h>
using namespace std;
constexpr int kMod = 1000000007;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  vector<pair<int, int>> ds = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
  for (int i = 0; i < H; ++i) cin >> s[i];
  for (int r = 0; r < H; ++r) {
    for (int c = 0; c < H; ++c) {
      if (s[r][c] == '.') continue;
      bool ok = false;
      for (auto [dr, dc] : ds) {
        int nr = r + dr;
        int nc = c + dc;
        if (nr < 0 || H <= nr || nc < 0 || W <= nc) continue;
        if (s[nr][nc] == '#') {
          ok = true;
          break;
        }
      }
      if (!ok) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
