#include <iostream>
#include <cstdio>

using namespace std;

int H, W;
char s[60][60];

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

	for (int i = 0; i < H; i++) {
		scanf_s("%s", &s[i]);
	}

	int dx[4] = { 1, -1, 0, 0 };
	int dy[4] = { 0, 0, 1, -1 };


	bool ans = true;
	for (int i = 0; i < H; i++) {
		for (int j = 0; i < W; j++) {
			if (s[i][j] == '#') {
				bool found = false;
				for (int k = 0; k < 4; k++) {
					int i2 = i + dx[k];
					int j2 = j + dy[k];
					if (i2 >= 0 && i2 < H && j2 >= 0 && j2 < W && s[i2][j2] == '#') {
						found == true;
					}
				}
				if (!found) ans = false;
			}
		}
	}

	cout << (ans ? "Yes" : "No") << endl;
	return 0;
}