#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {0, 1, 0, -1};
const int dy[4] = {1, 0, -1, 0};
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> M(H);
  for (int i = 0; i < H; i++) {
    cin >> M[i];
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (M[i][j] == '#') {
        int cnt = 0;
        for (int k = 0; k < 4; k++) {
          int nx = i + dx[k];
          int ny = j + dy[k];
          if (nx < 0 || ny < 0 || nx >= H || ny >= W) {
            continue;
          }
          if (M[nx][ny] == '#') {
            cnt++;
          }
        }
        if (cnt <= 2) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
