#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  int dx[4] = {-1, 0, 0, 1};
  int dy[4] = {0, -1, 1, 0};
  int a = 0;
  for (int i = 0; i < h; i++) {
    a = 0;
    for (int j = 0; j < w; j++) {
      int count = 0;
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int x = i + dx[k], y = j + dy[k];
          if (x >= 0 && x < h && y >= 0 && y < w) {
            if (s[x][y] == '#') count++;
          }
        }
        if (count == 0) goto end;
      }
    }
    a = 1;
  }
  if (a == 1) cout << "Yes";
end:
  cout << "No";
}
