#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y;
  cin >> x >> y;
  string s[x];
  for (int i = 0; i < x; i++) cin >> s[i];
  for (int i = 0; i < x; i++) {
    for (int j = 0; j < y; j++) {
      if (s[i][j] == '.') continue;
      if (s[i][j - 1] + s[i][j + 1] + s[i - 1][j] + s[i + 1][j] == '.' * 4) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
  return 0;
}
