import std.stdio;
import std.string;
auto dx=[0,-1,1,0],dy=[-1,0,0,1];
string[] s;
int h,w;
void main()
{
	readf("%d %d\n",&h,&w);
	for (int i=0;i<h;++i) s~=readln.strip();
	for (int y=0;y<h;++y)
	{
		for (int x=0;x<w;++x)
		{
			if (s[y][x]=='.') continue;
			bool flag=false;
			for (int i=0;i<4;++i)
			{
				int x2=x+dx[i],y2=y+dy[i];
				if (x2<0 || y2<0 || w<=x2 || h<=y2) continue;
				if (s[y2][x2]=='#')
				{
					flag=true;
					break;
				}
			}
			if (!flag)
			{
				write("No");
				return;
			}
		}
	}
	write("Yes");
}