#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long H, W;
  cin >> H >> W;
  vector<vector<long long>> s(H + 2, vector<long long>(W + 2, '.'));
  for (long long i = 1; i <= H; i++) {
    for (long long j = 1; j <= W; j++) {
      long long x;
      cin >> x;
      s[i][j] = x;
    }
  }
  for (long long i = 1; i <= H; i++) {
    for (long long j = 1; j <= H; j++) {
      if (s[i][j] == '.') {
        continue;
      }
      if (s[i - 1][j] != '#' && s[i + 1][j] != '#' && s[i][j - 1] != '#' &&
          s[i][j + 1] != '#') {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
