#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s;
  for (auto i = 0; i < H; ++i) {
    string temp;
    cin >> temp;
    s.push_back(temp);
  }
  auto result = true;
  int x[] = {0, 1, 0, -1};
  int y[] = {-1, 0, 1, 0};
  for (auto i = 0; i < H; ++i) {
    for (auto j = 0; j < W; ++j) {
      if (s[i][j] == '.') {
        continue;
      }
      result = false;
      for (auto k = 0; k < 4; ++k) {
        auto cx = j + x[k];
        auto cy = i + y[k];
        if (cx < 0 || cx >= W || cy < 0 || cy >= H) {
          continue;
        }
        if (s[cy][cx] == '#') {
          result = true;
          break;
        }
      }
    }
  }
  if (result) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
