#include <bits/stdc++.h>
using namespace std;
int main(int argc, const char* argv[]) {
  int cnt;
  int H, W;
  string A[55];
  bool flag;
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    cin >> A[i];
  }
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if (A[i][j] == '#') {
        flag = false;
        if (A[i - 1][j] == '#') flag = true;
        if (A[i][j - 1] == '#') flag = true;
        if (A[i][j + 1] == '#') flag = true;
        if (A[i + 1][j] == '#') flag = true;
        if (flag == false) break;
      }
      if (flag == false) break;
    }
  }
  if (flag == false)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
}
