#include <bits/stdc++.h>
using namespace std;
int main() {
  int dx[] = {0, 0, 1, -1};
  int dy[] = {1, -1, 0, 0};
  int H, W;
  cin >> H >> W;
  string s;
  vector<string> ss;
  for (int i = 0; i < H; i++) {
    cin >> s;
    ss.push_back(s);
  }
  bool ok = false;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (ss[i][j] == '#') {
        ok = false;
        for (int d = 0; d < 4; d++) {
          int a = dy[d] + i;
          int b = dx[d] + j;
          if (a < 0 || b < 0 || a >= H || b >= W) continue;
          if (ss[a][b] == '#') ok = true;
        }
      }
    }
    if (ok == false) {
      break;
    }
  }
  if (ok == false) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}
