#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> S(H + 1, vector<char>(W + 1, '.'));
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      cin >> S.at(i).at(j);
    }
  }
  int cnt = 0;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      char a = S.at(i).at(j);
      if (a == '#' && S[i][j - 1] != '#' && S[i - 1][j] != '#' &&
          S[i][j + 1] != '#' && S[i + 1][j] != '#')
        cnt++;
    }
  }
  puts(cnt == 0 ? "Yes" : "No");
}
