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