#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> Grid;
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < H; i++) {
    string tmp;
    cin >> tmp;
    Grid.emplace_back(tmp);
  }
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      int num = 0;
      for (int d = 0; d < 4; d++) {
        int cnt = 0;
        int ni = i + dy[d];
        int nj = j + dx[d];
        if (ni < 0 or H <= ni) continue;
        if (nj < 0 or W <= nj) continue;
        if (Grid[i][j] == '#') {
          if (Grid[ni][nj] == '#') {
            cnt++;
          }
        }
        if (cnt == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
