#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  int H, W;
  string S[50];
  bool flg = false;
  cin >> H >> W;
  for (long long i = 0; i < (long long)(H); i++) {
    cin >> S[i];
  }
  for (long long i = 0; i < (long long)(H); i++) {
    for (long long j = 0; j < (long long)(W); j++) {
      if (S[i][j] == '#') {
        flg = false;
        if (i < H - 1) {
          if (S[i + 1][j] == '#') flg = true;
        }
        if (j < W - 1) {
          if (S[i][j + 1] == '#') flg = true;
        }
        if (i > 0) {
          if (S[i - 1][j] == '#') flg = true;
        }
        if (j > 0) {
          if (S[i][j - 1] == '#') flg = true;
        }
        if (!flg) {
          i = H;
          j = W;
          break;
        }
      }
    }
  }
  if (flg) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
