#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W, di[4] = {1, 0, -1, 0}, dj[4] = {0, 1, 0, -1};
  cin >> H >> W;
  vector<string> s(H);
  for (int i = 0; i < H; i++) cin >> s[i];
  string ans = "Yes\n";
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '.') continue;
      ans = "No\n";
      for (int k = 0; k < 4; k++) {
        int ni = i + di[k], nj = j + dj[k];
        if (ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
        if (s[ni][nj] == '#') ans = "Yes\n";
      }
    }
  }
  cout << ans << endl;
}
