#include <bits/stdc++.h>
using namespace std;
long long MOD = 1000000007;
int main() {
  int h, w;
  cin >> h >> w;
  char s[60][60];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  int dx[] = {-1, 1, 0, 0};
  int dy[] = {0, 0, 1, -1};
  bool ans = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        bool f = false;
        for (int k = 0; k < 4; k++) {
          int posx = i + dx[k];
          int posy = j + dy[k];
          if (0 <= posx && posx <= w - 1 && 0 <= posy && posy <= h - 1) {
            if (s[posy][posx] == '#') {
              f = true;
            }
          }
        }
        if (!f) {
          ans = false;
        }
      }
    }
  }
  if (ans) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
