#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  int ans;
  int n[4][2] = {{-1, 0}, {0, -1}, {0, 1}, {1, 0}};
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        int k;
        for (k = 0; k < 4; k++) {
          if (i + n[k][0] >= 0 && i + n[k][0] < h && j + n[k][1] >= 0 &&
              j + n[k][1] < w && s[i + n[k][0]][j + n[k][1]] == '#')
            break;
        }
        if (k == 4) {
          ans = 0;
          break;
        }
      }
    }
    if (ans == 0) break;
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
