#include <bits/stdc++.h>
using namespace std;
string board[60];
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
int main(void) {
  int X, Y;
  cin >> X >> Y;
  for (int i = 0; i < X; i++) cin >> board[i];
  for (int i = 0; i < X; i++) {
    for (int j = 0; j < Y; j++) {
      if (board[i][j] == '#') {
        bool paint = false;
        for (int k = 0; k < 4; k++) {
          int x = i + dx[k];
          int y = j + dy[k];
          if (x >= 0 && x < X && y >= 0 && y < Y && board[x][y] == '#') {
            paint = true;
          }
        }
        if (!paint) {
          cout << 'No' << endl;
          return 0;
        }
      }
    }
  }
  cout << 'Yes' << endl;
  return 0;
}
