#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> S(H + 2);
  for (int i = 1; i < H + 1; i++) cin >> S[i];
  for (int i = 0; i < W + 2; i++) {
    S[0] = ".";
    S[H + 1] = ".";
  }
  for (int i = 1; i < H + 1; i++) {
    S[i] = "." + S[i] + ".";
  }
  string ans = "Yes";
  for (int i = 0; i < H + 2; i++) {
    for (int j = 0; j < W + 2; j++) {
      if (S[i][j] == '#') {
        if (S[i - 1][j] != '#' && S[i + 1][j] != '#' && S[i][j - 1] != '#' &&
            S[i][j + 1] != '#')
          ans = "No";
      }
    }
  }
  cout << ans << endl;
  return 0;
}
