#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[51][51];
  int f = true;
  int fb = false;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (s[i][j] == '#') {
        if (i != 0 && s[i - 1][j] == '#') fb = true;
        if (i != h - 1 && s[i + 1][j] == '#') fb = true;
        if (j != 0 && s[i][j - 1] == '#') fb = true;
        if (j != w - 1 && s[i][j + 1] == '#') fb = true;
        if (!fb) {
          f = false;
          break;
        }
      }
    }
  }
  cout << ((f) ? "Yes" : "No");
  return 0;
}
