#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
struct edge {
  long long to, costa, costb;
};
signed main() {
  long long h, w;
  cin >> h >> w;
  string s[h];
  for (long long i = 0; i < h; i++) cin >> s[i];
  for (long long i = 0; i < h; i++) {
    for (long long j = 0; j < w; j++) {
      if (s[i][j] == '.') continue;
      if (i != 0 && s[i - 1][j] == '#') continue;
      if (i != h && s[i + 1][j] == '#') continue;
      if (j != 0 && s[i][j - 1] == '#') continue;
      if (i != w && s[i][j + 1] == '#') continue;
      cout << "No";
      return 0;
    }
  }
  cout << "Yes";
  return 0;
}
