#include <bits/stdc++.h>
using namespace std;
int main(int argc, char *args[]) {
  int H, W;
  int cnt = 0;
  char s[100][100];
  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 - 1; j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] != '#' && s[i + 1][j] != '#' && s[i][j - 1] != '#' &&
            s[i][j + 1] != '#')
          cnt++;
      }
    }
  }
  if (cnt == 0)
    cout << 'Yes' << endl;
  else
    cout << 'No' << endl;
}
