#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      cin >> s[i][j];
    }
  }
  const int dx[4] = {1, -1, 0, 0};
  const int dy[4] = {0, 0, 1, -1};
  int cnt = 0;
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; ++k) {
          const int ni = i + dy[k];
          const int nj = j + dx[k];
          if (s[ni][nj] == '#') cnt++;
          if (ni < 0 || h <= ni) continue;
          if (nj < 0 || w <= nj) continue;
        }
        if (cnt == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
    cnt = 0;
  }
  cout << "Yes" << endl;
  return 0;
}
