#include <bits/stdc++.h>
using namespace std;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
char s[60][60];
bool f;
int main() {
  int h, w;
  cin >> h >> w;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (s[i][j] == '#') {
        for (int r = 0; r < 4; r++) {
          if (s[i + dx[r]][j + dy[r]] == '#') {
            f = true;
            break;
          }
        }
        if (!f) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
