#include <bits/stdc++.h>
using namespace std;
int H, W, i, j;
int back_i(int i) {
  if (i == 0) {
    return 0;
  } else {
    return i - 1;
  }
}
int back_j(int j) {
  if (j == 0) {
    return 0;
  } else {
    return j - 1;
  }
}
int push_i(int i, int H) {
  if (i == (H - 1)) {
    return H - 1;
  } else {
    return i + 1;
  }
}
int push_j(int j, int W) {
  if (j == (W - 1)) {
    return W - 1;
  } else {
    return j + 1;
  }
}
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> s(H, vector<char>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s.at(i).at(j);
    }
  }
  string judge = "Yes";
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s.at(i).at(i) == '#' && s.at(i).at(back_j(j)) != '#' &&
          s.at(i).at(push_j(j, W)) != '#' && s.at(push_i(i, H)).at(j) != '#' &&
          s.at(back_i(i)).at(j) != '#') {
        judge = "No";
        break;
      }
    }
  }
  cout << judge << endl;
  return 0;
}
