#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int H, W;
  cin >> H >> W;
  string s[50];
  for (int i = 0; i < (H); i++) cin >> s[i];
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < (H); i++) {
    for (int j = 0; j < (W); j++) {
      if (s[i][j] == '.') continue;
      int count = 0;
      for (int k = 0; k < 4; k++) {
        int x = j + dx[k];
        int y = i + dy[k];
        if (x < 0 || W < x) continue;
        if (y < 0 || H < y) continue;
        if (s[y][x] == '#') count++;
      }
      if (count == 0) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
