#include <bits/stdc++.h>
using namespace std;
constexpr long long INF = 1LL << 40;
const double INFD = 1e100;
const long long mod = 1000000007;
const double PI = 3.1415926535897932384626433832795028841971;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> field(H);
  for (int i = 0; i < H; i++) {
    cin >> field[i];
  }
  bool ans = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (field[i][j] == '#') {
        bool can = false;
        for (int k = 0; k < 4; k++) {
          int nx = j + dx[k];
          int ny = i + dy[k];
          if (nx < 0 || nx >= W || ny < 0 || ny >= H) continue;
          if (field[ny][nx] == '#') {
            can = true;
          }
        }
        if (!can) {
          cout << "check:" << i << " " << j << endl;
          ans = false;
        }
      }
    }
  }
  if (ans) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
