#include <bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
void solve() {}
int main() {
  int h, w;
  cin >> h >> w;
  string s[55];
  for (int i = 0; i < h; i++) {
    for (int k = 0; k < w; k++) {
      cin >> s[i][k];
    }
  }
  const int dx[4] = {0, 0, 1, -1};
  const int dy[4] = {1, -1, 0, 0};
  bool can = true;
  for (int i = 0; i < h; i++) {
    for (int k = 0; k < w; k++) {
      if (s[i][k] != '#') {
        continue;
      }
      int cnt = 0;
      bool found = false;
      for (int p = 0; p < 4; p++) {
        const int x = k + dx[p];
        const int y = i + dy[p];
        if (x >= 0 && x < w && y >= 0 && y < h) {
          if (s[y][x] == '#') {
            found = true;
          }
        }
      }
      if (found != true) {
        cout << "No" << endl;
        exit(0);
      }
    }
  }
  cout << "Yes" << endl;
}
