#include <bits/stdc++.h>
using namespace std;
const int maxn = 55;
int H, W;
string grid[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> H >> W;
  for (int i = 1; i <= H; i++) cin >> grid[i];
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (grid[i][j] == '#') {
        if (i - 1 >= 1 && grid[i - 1][j] == '#')
          continue;
        else if (j - 1 >= 1 && grid[i][j - 1] == '#')
          continue;
        else if (i + 1 <= H && grid[i + 1][j] == '#')
          continue;
        else if (j + 1 <= W && grid[i][j + 1] == '#')
          continue;
        else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
