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