#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string s[H][W];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  bool ans = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == "#") {
        bool up = false;
        bool left = false;
        bool down = false;
        bool right = false;
        if (i - 1 >= 0) {
          up = (s[i - 1][j] == "#");
        }
        if (j - 1 >= 0) {
          left = (s[i][j - 1] == "#");
        }
        if (i + 1 < H) {
          down = (s[i + 1][j] == "#");
        }
        if (j + 1 < W) {
          right = (s[i][j + 1] == "#");
        }
        if (up || left || down || right) {
          continue;
        } else {
          bool ans = false;
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  if (ans) {
    cout << "Yes" << endl;
  }
  return 0;
}
