#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int h, w;
  cin >> h >> w;
  char field[h][w];
  for (int i = 0; i < (h); ++i) cin >> field[i];
  int dh[4] = {-1, 0, 1, 0};
  int dw[4] = {0, -1, 0, 1};
  bool flag = true;
  for (int i = 0; i < (h); ++i)
    for (int j = 0; j < (w); ++j) {
      if (field[i][j] == '#') {
        bool can = false;
        for (int k = 0; k < (4); ++k) {
          int nh = i + dh[k];
          int nw = j + dw[k];
          if (0 <= nh && 0 <= nw && nh < h && nw < w && field[nh][nw] == '#')
            can = true;
        }
        if (!can) flag = false;
      }
    }
  cout << (flag ? "Yes" : "No") << '\n';
  return 0;
}
