#include <bits/stdc++.h>
using namespace std;
int main() {
  string res = "Yes";
  long H, W;
  cin >> H >> W;
  char S[100][100];
  for (int i = 1; i <= max(H, W); i++) {
    S[i][0] = '.';
    S[0][i] = '.';
  }
  for (int i = 1; i <= H; i++)
    for (int j = 1; j <= W; j++) cin >> S[H][W];
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (S[i][j] == '#') {
        if (S[i][j + 1] != '#' && S[i][j - 1] != '#' && S[i + 1][j] != '#' &&
            S[i - 1][j] != '#')
          res = "No";
      }
    }
  }
  cout << res << endl;
}
