#include <bits/stdc++.h>
using namespace std;
int main() {
  char grid[100][100];
  int n, m;
  cin >> n >> m;
  int x, y;
  for (x = 1; x <= n; x++) {
    for (y = 1; y <= m; y++) {
      cin >> grid[x][y];
    }
  }
  bool salah = 0;
  for (x = 1; x <= n; x++) {
    for (y = 1; y <= m; y++) {
      if (grid[x][y] == '#') {
        if (grid[x + 1][y] == '#' || grid[x - 1][y] == '#' ||
            grid[x][y + 1] == '#' || grid[x][y - 1] == '#') {
          break;
        } else {
          salah = 1;
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  if (salah == 0) {
    cout << "Yes" << endl;
  }
  return 0;
}
