#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
template <class T>
using v = vector<T>;
template <class T>
using vv = v<v<T>>;
int main() {
  int H, W;
  cin >> H >> W;
  vector<int> dx{1, 0, -1, 0};
  vector<int> dy{0, 1, 0, -1};
  vv<char> s(H, v<char>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        bool r = false;
        for (int dir = 0; dir < 4; dir++) {
          int d_h = H + dx[dir];
          int d_w = W + dy[dir];
          if (d_h < 0 || d_w < 0 || d_h >= H || d_w >= W) continue;
          if (s[d_h][d_w] == '#') r = true;
        }
        if (r == false) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
