#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  char A[52][52] = {};
  int i, j;
  bool ans = true;
  cin >> H >> W;
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      scanf("%c", &A[i][j]);
    }
  }
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      if (A[i][j] == '#') {
        if (A[i][j + 1] != '#' && A[i][j - 1] != '#' && A[i - 1][j] != '#' &&
            A[i + 1][j] != '#')
          ans = false;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
