#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e9;
const long long MOD = 1e9 + 7;
int main() {
  int h, w;
  cin >> h >> w;
  char c[h][w];
  for (long long i = 0; i < (h); i++) {
    for (long long j = 0; j < (w); j++) {
      cin >> c[i][j];
    }
  }
  for (long long i = 1; i < (h - 1); i++) {
    for (long long j = 1; j < (w - 1); j++) {
      int cnt = 0;
      for (long long k = 0; k < (4); k++) {
        if (c[i][j] == '.') cnt++;
      }
      if (cnt == 4) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
