#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int i = 0, j = 0;
  string bw[60];
  int h, w;
  cin >> h >> w;
  for (i = 0; i < h; i++) {
    cin >> bw[i];
  }
  int check = 0;
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      if (bw[i][j] == '#') {
        if (bw[i - 1][j] == '#' || bw[i + 1][j] == '#' || bw[i][j - 1] == '#' ||
            bw[i][j + 1] == '#') {
          check = 0;
        } else {
          check = 1;
        }
      }
    }
  }
  if (check) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}
