#include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int H, W;
int main() {
  cin >> H >> W;
  char s[H + 2][W + 2];
  for (int i = 0; i < (int)(H + 2); i++) {
    for (int j = 0; j < (int)(W + 2); j++) {
      if (i == 0 || i == H + 1 || j == 0 || j == W + 1) s[i][j] = '.';
      cin >> s[i][j];
    }
  }
  for (int i = (int)(1); i < (int)(H + 1); i++) {
    for (int j = (int)(1); j < (int)(W + 1); j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] == '#' || s[i + 1][j] == '#' || s[i][j - 1] == '#' ||
            s[i][j + 1] == '#') {
          continue;
        } else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
}
