#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char m[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> m[i][j];
    }
  }
  bool a = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (m[i][j] == '#') {
        if (i == w - 1) {
          if (m[i - 1][j] != '#' && m[i][j + 1] != '#') a = false;
        }
        if (j == h - 1) {
          if (m[i + 1][j] != '#' && m[i][j - 1] != '#') a = false;
        }
        if (j != h - 1 && i != w - 1) {
          if (m[i + 1][j] != '#' && m[i][j + 1] != '#') a = false;
        }
      }
    }
  }
  if (a) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
