#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> S(H);
  for (int i = 0; i < H; i++) {
    cin >> S.at(i);
  }
  const vector<int> dx = {0, 0, 1, -1};
  const vector<int> dy = {1, -1, 0, 0};
  int flag = 0;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (S.at(i).at(j) == '#') {
        flag = 1;
        for (int k = 0; k < 4; k++) {
          int ni = i + dx.at(k);
          int nj = j + dy.at(k);
          if (ni < 0 || ni >= H) continue;
          if (nj < 0 || nj >= W) continue;
          if (S.at(ni).at(nj) == '#') {
            flag = 0;
          }
        }
      }
    }
  }
  if (flag == 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
}
