#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];
    }
  }
  bool flag = false;
  for (int i = 1; i < H - 1; i++) {
    for (int j = 1; j < W - 1; j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] != '#' && s[i][j - 1] != '#' && s[i + 1][j] != '#' &&
            s[i][j + 1] != '#') {
          flag = 1;
        }
      } else {
        if (s[i - 1][j] != '.' && s[i][j - 1] != '.' && s[i + 1][j] != '.' &&
            s[i][j + 1] != '.') {
          flag = 1;
        }
      }
    }
  }
  if (flag)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
