#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for (int i = 0; i < H; i++) cin >> s[i];
  int dx[4] = {0, 0, 1, -1};
  int dy[4] = {1, -1, 0, 0};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      bool ok = false;
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int X = i + dx[k];
          int Y = j + dy[k];
          if (0 <= X && X < W && 0 <= Y && Y < H && s[X][Y] == '#') ok = true;
        }
        if (!ok) {
          cout << "No"
               << "\n";
          return 0;
        }
      }
    }
  }
  cout << "Yes"
       << "\n";
  return 0;
}
