#include <iostream>
using namespace std;

int main() {
	int h, w;
	cin >> h >> w;
	char s[h][w];
	bool flag = true;
	for(int i = 0; i < h; i++){
		cin >> s[h];
	}
	for (int i = 0; i < h; i++){
		for (int j = 0; j < w; j++){
			for(int k = 0; k < 4; k++){
				if (k == 0 && i != 0 && s[h - 1][w] == '#'){
					flag == true;
					break
				}else if(k == 1 && i != h - 1 && s[h + 1][w] == '#'){
					flag == true;
					break
				}else if(k == 2 && j != 0 && s[h][w - 1] == '#'){
					flag == true;
					break;
				}else if(k == 3 && j != w - 1 && s[h][s + 1] == '#'){
					flag == true;
					break;
				}else{
					flag == false;
				}
			}
		}
	}
	if (flag == true){
		cout << "Yes" << endl;
	}else{
		cout << "No" << endl;
	}
	return 0;
}