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

char a[51][51];

signed main(){

  int h,w; cin >> h >> w;
  for(int i = 0; i < h; i++){
    for(int j = 0; j < w; j++){
      cin >> a[i][j];
    }
  }

  int flag = 1;
  for(int i = 0; i < h; i++){
    for(int j = 0; j < w; j++){
      if(a[i][j] == '#'){
        if(a[i+1][j] != '#' && a[i][j-1] != '#' && a[i-1][j] != '#' && a[i][j+1] != '#') flag = 0;
      }
    }
  }
  cout << (flag ? "Yes" : "No") << endl;

  return 0;
}
