#include<iostream>
using namespace std;

int n,m,f;
char s[51][51];
	
int main(){ 

	cin>>n>>m;
	
		for(int i=1;i<=n;i++){
			for(int j=1;j<=m;j++)
				cin>>s[i][j];
		}
					
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
				if (c[i][j] == '#' && c[i][j - 1] == '#' && c[i - 1][j] == '#' && c[i][j + 1] == '#' && c[i + 1][j] == '#')	
				{
					f=1;break;
				}	
		}	
	}				
	if(f==1)
		cout<<"Yes"<<endl;
	else
		cout<<"No"<<endl;
		
	return 0;
}