#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string s[50];
  for (int i = 0; i < w; i++) cin >> s[i];
  const int dx[4] = {0, 0, 1, -1};
  const int dy[4] = {1, -1, 0, 0};
  bool ok = true;
  for (int i = 0; i < w; i++) {
    for (int j = 0; j < h; j++) {
      if (s[i][j] != '#') continue;
      bool ok2;
      for (int k = 0; k < 4; k++) {
        const int ni = i + dx[k];
        const int nj = j + dy[k];
        if (ni < 0 or ni >= w) continue;
        if (nj < 0 or nj >= h) continue;
        if (s[ni][nj] == '#') ok2 = true;
        continue;
      }
      if (ok2) continue;
      ok = false;
    }
  }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
