#include <bits/stdc++.h>
using namespace std;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  string *s = new string[h];
  for (int i = 0; i < h; i++) cin >> s[i];
  bool can = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int nx = i + dx[k];
          int ny = j + dy[k];
          if (nx < 0 || h <= nx || ny < 0 || w <= ny || s[nx][ny] == '#')
            continue;
          can = false;
        }
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
