#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int H, W;
  cin >> H >> W;
  string s[H];
  for (int i = (int)0; i < (int)H; i++) cin >> s[i];
  int dx[] = {0, -1, 1, 0};
  int dy[] = {-1, 0, 0, 1};
  for (int i = (int)0; i < (int)H; i++)
    for (int j = (int)0; j < (int)W; j++) {
      if (s[j][i] == '#') {
        bool flag = true;
        for (int k = (int)0; k < (int)4; k++) {
          int nx = j + dx[k];
          int ny = i + dy[k];
          if (0 <= nx and nx < W and 0 <= ny and ny < H) {
            if (s[ny][nx] == '#') flag = false;
          }
        }
        if (flag) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  cout << "Yes" << endl;
}
