#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  int H, W;
  cin >> H >> W;
  vector<vector<int>> s(H, vector<int>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      char c;
      cin >> c;
      if (c == '#')
        s[i][j] = 1;
      else
        s[i][j] = 0;
    }
  }
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, 1, 0, -1};
  bool ok = true;
  for (int h = 0; h < H; h++) {
    for (int w = 0; w < W; w++) {
      if (s[h][w] == 1) {
        int neighbor = 0;
        for (int i = 0; i < 4; i++) {
          int hi = h + dy[i];
          int wi = w + dx[i];
          if (hi < 0 || hi >= H || wi < 0 || wi >= W) continue;
          if (s[hi][wi] == 1) neighbor++;
        }
        if (neighbor == 0) {
          ok = false;
          break;
        } else {
          ok = true;
        }
      }
    }
  }
  if (ok) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
