#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) cin >> s[i][j];
  }
  bool flag = 1;
  vector<int> di = {0, -1, 0, 1}, dj = {1, 0, -1, 0};
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        int cnt = 0;
        for (int k = 0; k < 4; k++) {
          int ni = i + di[k], nj = j + dj[k];
          if (ni >= 0 && ni < h && nj >= 0 && nj < w) {
            if (s[ni][nj] == '#') ++cnt;
          }
        }
        if (cnt == 0) flag = 0;
      }
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
