#include <bits/stdc++.h>
using namespace std;

int main() {
  int H, W;
  cin >> H >> W;
  
  string a[H];
  
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, 1, 0, -1};
  
  for (int i = 0; i < H; i++) {
    cin >> a[i];
  }
  
  string ans = "Yes";
  
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      
      if (a[i].at[j] == '#') {
        for (int k = 0; k < 4; k++) {
          ans = "No";
          
          if (i + dy[k] < 0 || i + dy[k] >= H 
              || j + dx[k] < 0 || j + dx[k] >= W) {
            continue;
          }
          
          if (a[i + dy[k]].at(j + dx[k]) == '#') {
            ans = "Yes";
          }
        }
        if (ans == "No") {
          cout << "No" << endl;
          return 0;
        }
      } 
    }
  }
  cout << ans << endl;
}