#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string s_list[H];
  for (int i = 0; i < H; ++i) {
    cin >> s_list[i];
  }
  const int dx[4] = {-1, 0, 0, 1};
  const int dy[4] = {0, -1, 1, 0};
  bool flag = false;
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if (s_list[i][j] == '#') {
        bool can = false;
        for (int k = 0; k < 4; ++k) {
          int ni = i + dx[k];
          int nj = j + dy[k];
          if (ni < 0 or ni >= H) continue;
          if (nj < 0 or nj >= W) continue;
          if (s_list[ni][nj] == '#') {
            can = true;
          }
        }
        if (!can) {
          break;
        }
      }
    }
    if (!flag) {
      break;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
