#include <bits/stdc++.h>
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
using namespace std;
int dx[] = {1, 0, 0, -1};
int dy[] = {0, -1, 1, 0};
string bord[60];
int main() {
  int h, w;
  cin >> h >> w;
  for (int i = 0; i < (int)(h); i++) cin >> bord[i];
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (bord[i][j] == '#') {
        int a = 1;
        for (int k = 0; k < (int)(4); k++) {
          int x = i + dx[k];
          int y = j + dy[k];
          if (x >= 0 && x < h && y >= 0 && y < w && bord[x][y] == '#') a = 0;
        }
        if (a) cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
