#include <bits/stdc++.h>
using namespace std;
char c[55][55]; int h, w, cnt;
int main() 
{
	cin >> h >> w;
	for (int i = 1; i <= H; i++) {
		for (int j = 1; j <= W; j++) 
			cin >> c[i][j];
	}
	for (int i = 1; i <= H; i++) {
		for (int j = 1; j <= W; j++) {
			if (c[i][j] == '#' && c[i][j - 1] != '#' && c[i - 1][j] != '#' && c[i][j + 1] != '#' && c[i + 1][j] != '#') 
				cnt++;
		}
	}
	if (cnt == 0) cout << "Yes" << endl;
	else cout << "No" << endl;
	return 0;
}