#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
int main(void) {
  cin.tie(0);
  cout.tie(0);
  ios::sync_with_stdio(false);
  int h, w;
  cin >> h >> w;
  vector<string> vec(h);
  for (long long i = 0; i < (long long)h; ++i) cin >> vec[i];
  long long flag = 4;
  for (long long i = 0; i < (long long)h; ++i) {
    for (long long j = 0; j < (long long)w; ++j) {
      if (i == 0 || i == h) --flag;
      if (j == 0 || j == w) --flag;
      int cta = 0;
      if (j + 1 >= w) continue;
      if (j + 1 < w && vec[i][j + 1] == '.') ++cta;
      if (j - 1 >= 0 && vec[i][j - 1] == '.') ++cta;
      if (i + 1 < h && vec[i + 1][j] == '.') ++cta;
      if (i - 1 >= 0 && vec[i - 1][j] == '.') ++cta;
      if (cta == flag) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
