#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  string s[h];
  for (int i = 1; i <= h; i++) cin >> s[i - 1];
  int dx[4] = {-1, 0, 1, 0};
  int dy[4] = {0, 1, 0, -1};
  bool isolate = false;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (s[i - 1][j - 1] == '.') {
        isolate = false;
        break;
      }
      isolate = true;
      for (int k = 1; k <= 4; k++) {
        int sx = i + dx[k - 1];
        int sy = j + dy[k - 1];
        if (!(sx < 1 || sx > h || sy < 1 || sy > w)) {
          if (s[sx - 1][sy - 1] == '#') isolate = false;
        }
      }
      if (isolate == true) break;
    }
    if (isolate == true) break;
  }
  cout << (isolate ? "No" : "Yes") << endl;
}
