#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W, i, j, answer = 0;
  char s[60][60] = {};
  cin >> H >> W;
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      cin >> s[i][j];
    }
  }
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      if (s[i][j] = '#') {
        if (s[i - 1][j] != '#' && s[i + 1][j] != '#' && s[i][j - 1] != '#' &&
            s[i][j + 1] != '#') {
          answer++;
        }
      }
    }
  }
  if (answer == 0) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
