#include <bits/stdc++.h>
using namespace std;
char c[52][52];
int h, w;
bool check(int a, int b) {
  if (c[a + 1][b] == '#' || c[a - 1][b] == '#' || c[a][b + 1] == '#' ||
      c[a][b - 1] == '#')
    return true;
  return false;
}
int main() {
  cin >> h >> w;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> c[i][j];
    }
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (check(i, j)) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
}
