#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char canpas[50][51];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> canpas[i][j];
    }
  }
  bool ispaint = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < H; j++) {
      if (canpas[i][j] == '#' &&
          (canpas[i][j + 1] == '#' || canpas[i + 1][j] == '#' ||
           canpas[i - 1][j] == '#' || canpas[i][j - 1] == '#')) {
        ispaint = true;
      } else if (canpas[i][j] == '#') {
        ispaint = false;
        break;
      }
    }
  }
  if (ispaint) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
