#include<iostream>
using namespace std;
int main(){ 
	int i,j,n,m,f=0;
	cin>>n>>m;
	char s[n+5][m+5];
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			cin>>s[i][j];
		}
	}
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){	
			if((s[i][j]=='#')&&(s[i-1][j]=='#'||s[i+1][j]=='#'||s[i][j-1]=='#'||s[i][j+1]=='#')){	
				f=1;
			}	
		}
	} 
	if(f==1){
		cout<<"Yes"<<endl;
	}
	else(f==0){
		cout<<"No"<<endl;
	}	
	return 0;
}
