#include <bits/stdc++.h>
using namespace std;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, -1, 0};
int main() {
  int h, w;
  cin >> h >> w;
  string B[50];
  for (int i = 0; i < (h); i++) cin >> B[i];
  for (int i = 0; i < (h); i++)
    for (int j = 0; j < (w); j++)
      if (B[i][j] == '#') {
        bool ok = false;
        for (int k = 0; k < (4); k++) {
          int y = i + dy[k], x = j + dx[k];
          if (0 <= y && y < h && 0 <= x && x < w && B[i][j] == '#') ok = true;
        }
        if (!ok) {
          cout << "No" << endl;
          return 0;
        }
      }
  cout << "Yes" << endl;
  return 0;
}
