#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < w; i++) {
    for (int j = 0; j < h; j++) {
      cin >> s[i][j];
    }
  }
  int cnt_repeat = 0;
  for (int i = 0; i < w; i++) {
    cnt_repeat = 0;
    for (int j = 0; j < h; j++) {
      if (s[i][j] == '#') {
        cnt_repeat++;
      } else {
        if (cnt_repeat == 1) {
          if (i != 0 && s[i - 1][j - 1] == '#') {
          } else if (i != w && s[i + 1][j - 1] == '#') {
          } else {
            cout << "No" << endl;
            return 0;
          }
        }
        cnt_repeat = 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
