#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  char S[50][50];
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> S[i][j];
    }
  }
  int count = 0;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') {
        if (i - 1 >= 0) count += S[i - 1][j] == '#';
        if (j - 1 >= 0) count += S[i][j - 1] == '#';
        if (i + 1 <= H - 1) count += S[i + 1][j] == '#';
        if (j + 1 <= W - 1) count += S[i][j + 1] == '#';
        if (count == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
}
