#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string str;
  int field[H + 2][W + 2];
  int i, j;
  for (i = 1; i <= H; i++) {
    field[i][0] = 1;
    field[i][W + 1] = 1;
  }
  for (j = 1; j <= W; j++) {
    field[0][j] = 1;
    field[H + 1][j] = 1;
  }
  for (i = 1; i <= H; i++) {
    cin >> str;
    for (j = 1; j <= W; j++) {
      if (str[j] == '#') {
        field[i][j] = 0;
      } else {
        field[i][j] = 1;
      }
    }
  }
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      if (field[i][j] == 0) {
        if (field[i + 1][j] * field[i - 1][j] * field[i][j + 1] *
                field[i][j - 1] !=
            0) {
          cout << "No";
          return 0;
        }
      }
    }
  }
  cout << "Yes";
  return 0;
}
