#include <iostream>
using namespace std;

int main()
{
	int H, W;
	cin >> H >> W;

	char S[55][55];
	string s;
	for (int i = 1; i <= H; i++)
	{
		cin >> s;
		for (int j = 1; j <= W; j++)
		{
			S[i][j] = s[j - 1];
		}
	}

	for (int i = 1; i <= H; i++)
	{
		for (int j = 1; j <= W; j++)
		{
			if (S[i][j]=='#' and S[i][j+1]!='#' and S[i][j - 1] != '#' and S[i+1][j] != '#' and S[i-1][j] != '#')
			{
				cout << "No";
				return 0;
			}
		}

	}
	cout << "Yes";
	return 0;
}
