#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using p = pair<int, int>;
int main() {
  int h, w;
  int cnt;
  string s[55];
  const int dx[] = {0, 1, -1, 0};
  const int dy[] = {1, 0, 0, -1};
  cin >> h >> w;
  for (int i = 0; i < (int)(h); i++) cin >> s[i];
  bool can = true;
  for (int i = 0; i < (int)(h); i++)
    for (int j = 0; j < (int)(w); j++) {
      if (s[i][j] == '#') {
        bool sharp = false;
        for (int d = 0; d < 4; d++) {
          int x = i + dx[d];
          int y = j + dy[d];
          if (x < 0 || h <= x) continue;
          if (y < 0 || w <= y) continue;
          if (s[x][y] == '#') sharp = true;
        }
        if (!sharp) can = true;
      }
    }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
