#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h + 2][w + 2];
  fill(s[0], s[w + 2], '.');
  int x[4] = {0, 1, 0, -1};
  int y[4] = {-1, 0, 1, 0};
  for (int i = 0; i < (h); ++i)
    for (int j = 0; j < (w); ++j) cin >> s[i + 1][j + 1];
  cout << endl;
  for (int i = (1); i < (h + 1); ++i) {
    for (int j = (1); j < (w + 1); ++j) {
      bool flag = false;
      if (s[i][j] == '#') {
        for (int k = 0; k < (4); ++k) {
          if (s[i + y[k]][j + x[k]] == '#') {
            flag = true;
          }
        }
        if (!flag) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
