#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  bool black;
  string answer = "Yes";
  string board[50];
  for (int i = 0; i < h; ++i) cin >> board[i];
  const int dx[4] = {1, 0, -1, 0};
  const int dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (board[i][j] == '#') {
        black = false;
        for (int d = 0; d < 4; ++d) {
          const int ni = i + dy[d];
          const int nj = j + dx[d];
          if (ni < 0 or h <= ni) continue;
          if (nj < 0 or w <= nj) continue;
          if (board[ni][nj] == '#') black = true;
        }
      }
      answer = "No";
    }
  }
  cout << answer << endl;
}
