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