#include <iostream>
#include <string>
#include <algorithm>
#include<math.h>
using namespace std;
int main(){
	int H, W;
	int res=0;
	int fail=0;
	string S[100000];
	cin >> H >> W;
	for(int n=1; n<=H; n++){
		for(int i=1; i<=W; i++)
		cin >> S[n][i];
	}
	for(int n=1; n<=H; n++){
		for(int i=1; i<=W; i++){
		if(S[n][i]=='#'){
			if(S[n+1][i]=='#' || S[n-1][i]=='#' || S[n][i+1]=='#' || S[n][i-1]=='#'){
				res=1;
			}else{
				fail=1;
				break;
			}
		}
		if(fail==1) break;
	}

	if(H==1&&W==1){
cout << "Yes"<<endl;
	}
	else if(fail==1){
		cout << "No"<<endl;
	}else 	{
cout << "Yes"<<endl;
	}
	return 0;
}