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