#include <bits/stdc++.h>
2.using namespace std;
3.int main(){
4.	int a,b;
5.	cin>>a>>b;
6.	char k[51][51];
7.	for(int i=0;i<a;i++){
8.		cin>>k[i];
9.	}
10.	for(int i=0;i<a;i++){
11.		for(int j=0;j<b;j++){
12.			if(k[i][j]='#'){
13.				if(k[i-1][j]!='#'&&k[i][j-1]!='#'&&k[i+1][j]!='#'&&k[i][j+1]!='#'){
14.					cout<<"No";
15.					return 0;
16.			}
17.		}
18.	}
19.}
20.cout<<"Yes";
21. 
22.	
23.}

#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,b;
	cin>>a>>b;
	char k[51][51];
	for(int i=0;i<a;i++){
		cin>>k[i];
	}
	for(int i=0;i<a;i++){
		for(int j=0;j<b;j++){
			if(k[i][j]='#'){
				if(k[i-1][j]!='#'&&k[i][j-1]!='#'&&k[i+1][j]!='#'&&k[i][j+1]!='#'){
					cout<<"No";
					return 0;
			}
		}
	}
}
cout<<"Yes";

	
}