import std.stdio, std.conv, std.string;
import std.algorithm, std.array, std.container;
import std.numeric, std.math;
import core.bitop;

string RD() { return chomp(readln()); }

long mod = pow(10, 9) + 7;
long moda(long x, long y) { return (x + y) % mod; }
long mods(long x, long y) { return ((x + mod) - (y % mod)) % mod; }
long modm(long x, long y) { return (x * y) % mod; }

void main()
{
	auto tokens = RD.split;
	auto H = tokens[0].to!long;
	auto W = tokens[0].to!long;
	
	string[] s;
	foreach (i; 0..H)
	{
		s ~= RD;
	}

	bool visit(long i, long j)
	{
		if (i < 0 || i >= H || j < 0 || j >= W) return false;

		return s[i][j] == '#';
	}

	bool cant = false;
	foreach (i; 0..H)
	{
		foreach (j; 0..W)
		{
			if (s[i][j] == '.') continue;

			bool r = false;
			r |= visit(i-1, j);
			r |= visit(i+1, j);
			r |= visit(i, j-1);
			r |= visit(i, j+1);
			if (!r) cant = true;
		}
	}

	writeln(cant ? "No" : "Yes");
	stdout.flush();
}