#include <bits/stdc++.h>
using namespace std;
int a, b, i, j, n, m;
int main() {
  char x[a][b];
  string ans;
  cin >> a >> b;
  for (i = 0; i < a; i++) {
    for (j = 0; j < b; j++) {
      cin >> x[i][j];
    }
  }
  for (n = 0; n < a; n++) {
    for (m = 0; m < b; m++) {
      if (x[n][m] == '#' && x[n + 1][m] != '#' ||
          x[n][m] == '#' && x[n - 1][m] != '#' ||
          x[n][m] == '#' && x[n][m + 1] != '#' ||
          x[n][m] == '#' && x[n][m - 1] != '#') {
        ans = "No";
      } else
        ans = "Yes";
    }
  }
  cout << ans;
  return 0;
}
