#include <bits/stdc++.h>
using namespace std;
const long long INF = 1LL << 60;
using Graph = vector<vector<int>>;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
inline int gcd(int a, int b) {
  if (a % b == 0) {
    return b;
  } else {
    return gcd(b, a % b);
  }
}
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) {
    cin >> s[i];
  }
  for (int iy = 0; iy < h; iy++) {
    for (int ix = 0; ix < w; ix++) {
      if (s[ix][iy] == '.') {
        continue;
      }
      bool okay = false;
      for (int k = 0; k < 4; k++) {
        int y = iy + dy[k];
        int x = ix + dx[k];
        if (0 <= x && 0 <= y && x < w && y < h && s[x][y] == '#') {
          okay = true;
          break;
        }
      }
      if (okay == false) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
