#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(W);
  for (int i = 0; i < W; i++) cin >> s[i];
  bool exist = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '.') continue;
      bool canpaint = false;
      if (i > 0)
        if (s[i - 1][j] == '#') canpaint = true;
      if (j > 0)
        if (s[i][j - 1] == '#') canpaint = true;
      if (i < H - 1)
        if (s[i + 1][j] == '#') canpaint = true;
      if (j < W - 1)
        if (s[i][j + 1] == '#') canpaint = true;
      if (!canpaint) {
        exist = false;
        break;
      }
    }
    if (!exist) break;
  }
  if (exist)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
