#include <bits/stdc++.h>
using namespace std;
vector<int> dx = {1, 0, -1, 0};
vector<int> dy = {0, 1, 0, -1};
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for (int i = 0; i < H; i++) {
    cin >> s[i];
  }
  bool res = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        bool exist = false;
        for (int k = 0; k < 4; k++) {
          if (0 <= i + dx[k] && i + dx[k] < H && 0 <= j + dy[k] &&
              j + dy[k] < W && s[i + dx[k]][j + dy[k]] == '#') {
            exist = true;
            break;
          }
        }
        res = exist;
      }
    }
  }
  if (res) {
    cout << "Yes";
  } else {
    cout << "No";
  }
  cout << endl;
  return 0;
}
