#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 possib = true;
  for (int i = 1; i < H; ++i) {
    for (int j = 1; j < W; ++j) {
      if (s[i][j] == '#') {
        if (s[i + 1][j] == '#' || s[i - 1][j] == '#') {
          possib = true;
        } else {
          if (s[i][j + 1] == '#' || s[i][j - 1] == '#') {
            possib = true;
          } else {
            possib = false;
            break;
          }
        }
      }
    }
  }
  if (possib) {
    cout << "Yes";
  } else {
    cout << "No";
  }
}
