#include <bits/stdc++.h>
using namespace std;
char c[41][41];
int dx[4] = {1, -1, 0, 0}, dy[4] = {0, 0, 1, -1};
int main() {
  int n, m;
  cin >> n >> m;
  memset(c, '.', sizeof(c));
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) cin >> c[i][j];
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++)
      if (c[i][j] == '#') {
        bool can = 0;
        for (int k = 0; k < 4; k++)
          if (c[dx[k] + i][dy[k] + j] == '#') can = 1;
        if (!can) {
          cout << "No";
          return 0;
        }
      }
  cout << "Yes";
}
