#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string s[55];
  int x[4] = {0, -1, 1, 0};
  int y[4] = {-1, 0, 0, 1};
  bool ans = true;
  for (int i = 0; i < h; ++i) {
    cin >> s[i];
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '#') {
        bool continuity = false;
        for (int k = 0; k < 4; ++k) {
          if (s[i + y[k]][j + x[k]] == '#') {
            continuity = true;
          }
        }
        if (!continuity) {
          ans = false;
          break;
        }
      }
    }
  }
  if (ans) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
