#include <bits/stdc++.h>
using namespace std;
int main() {
  int A, B, N, M, H, W;
  int i, j, k;
  int min = 1000000000;
  int max = 0;
  int a, b, c, d;
  int count = 0, count_two = 0, v;
  string cam[50];
  cin >> H >> W;
  for (i = 0; i < H; i++) cin >> cam[i];
  for (i = 0; i < H; i++) {
    for (j = 0; j < W; j++) {
      if (cam[i][j] == '#') {
        if (cam[i + 1][j] == '#' || cam[i - 1][j] == '#' ||
            cam[i][j + 1] == '#' || cam[i][j - 1] == '#') {
          continue;
        } else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
