#include <iostream>

int main()
{
	bool pos = true;
	
	int h, w;
	cin >> h >> w;
	
	char grid[h][w];
	
	for (int i = 0; i < h; i++)
	{
		for (int j = 0; j < w; j++)
		{
			char val;
			cin >> val;
			grid[i][j] = val;
		}
	}
	
	for (int i = 0; i < h-1; i++)
	{
		for (int j = 0; j < w-1; j++)
		{
			if ((grid[i][j] == '#' && grid[i][j+1] != '#') || (grid[i][j] == '#' && grid[i+1][j] != '#'))
			{
				pos = false;
			}
		}
	}
	
	if (pos)
		std::cout << "Yes" << std::endl;
	else
		std::cout << "No" << std::endl;
		
	return 0;
}
