#include <bits/stdc++.h>
using namespace std;
const int MAX = 60;
char m[MAX][MAX];
int dir[5] = {1, 0, -1, 0, 1};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int l, c;
  cin >> l >> c;
  for (int i = 1; i <= l; i++)
    for (int j = 1; j <= c; j++) cin >> m[i][j];
  for (int i = 1; i <= l; i++) {
    for (int j = 1; j <= c; j++) {
      bool ok = false;
      for (int k = 0; k < 4; k++)
        if (m[i + dir[k]][j + dir[k + 1]] == '#') ok = true;
      if (!ok) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
