#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int H, W;
  cin >> H >> W;
  vector<int> y = {1, 0, -1, 0};
  vector<int> x = {0, 1, 0, -1};
  vector<string> s(H);
  bool ans = false;
  for (int i = 0; i < H; i++) {
    cin >> s[i];
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '.') {
        continue;
      }
      bool check = false;
      for (int k = 0; k < 4; k++) {
        int ny = i + y[k];
        int nx = j + x[k];
        if (ny < 0 || ny >= H || nx < 0 || nx >= W) {
          continue;
        }
        if (s[ny][nx] == '#') {
          check = true;
          break;
        }
      }
      if (!check) {
        ans = false;
        break;
      } else {
        ans = true;
      }
    }
  }
  if (ans) {
    cout << "yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
