#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string board[50];
  const int dx[4] = {1, 0, -1, 0};
  const int dy[4] = {0, 1, 0, -1};
  bool flag = true;
  for (int i = 0; i < h; i++) cin >> board[i];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      bool t = false;
      if (board[i][j] == '.') continue;
      for (int d = 0; d < 4; d++) {
        const int ni = i + dy[d];
        const int nj = j + dx[d];
        if (ni < 0 || ni >= h) continue;
        if (nj < 0 || nj >= w) continue;
        if (board[ni][nj] == '#') {
          t = true;
          break;
        }
      }
      flag = t;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
