
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskX solver = new TaskX();
		solver.solve(1, in, out);
		out.close();
	}

	static int INF = 1 << 30;
	static int modP = 1000000007;

	static int[] mh = {0,-1,1,0};
	static int[] mw = {-1,0,0,1};

	static class TaskX {
		public void solve(int testNumber, InputReader in, PrintWriter out) {

			int h = in.nextInt(), w = in.nextInt();
			char[][] s = new char[h][w];
			for (int i = 0; i < h; i++) {
				s[i] = in.nextString().toCharArray();
			}

			boolean[][] visited = new boolean[h][w];
			for (int i = 0; i < h; i++) {
				for (int j = 0; j < w; j++) {
					if (s[i][j] == '#') {
						for (int k = 0; k < 4; k++) {
							if (0 <= i+mh[k] && i+mh[k] < h && 0 <= j+mw[k] && j+mw[k] < h) {
								if (s[i+mh[k]][j+mw[k]] == '#') {
									visited[i][j] = true;
									visited[i+mh[k]][j+mw[k]] = true;
								}
							}
						}
					}
				}
			}

			for (int i = 0; i < h; i++) {
				for (int j = 0; j < w; j++) {
					if (s[i][j] == '#') {
						if (visited[i][j]) {
							continue;
						} else {
							out.println("No");
							return;
						}
					}
				}
			}

			out.println("Yes");

		}
	}

	static class InputReader {
		BufferedReader in;
		StringTokenizer tok;

		public String nextString() {
			while (!tok.hasMoreTokens()) {
				try {
					tok = new StringTokenizer(in.readLine(), " ");
				} catch (IOException e) {
					throw new InputMismatchException();
				}
			}
			return tok.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(nextString());
		}

		public long nextLong() {
			return Long.parseLong(nextString());
		}

		public double nextDouble() {
			return Double.parseDouble(nextString());
		}

		public int[] nextIntArray(int n) {
			int[] res = new int[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextInt();
			}
			return res;
		}

		public long[] nextLongArray(int n) {
			long[] res = new long[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextLong();
			}
			return res;
		}

		public InputReader(InputStream inputStream) {
			in = new BufferedReader(new InputStreamReader(inputStream));
			tok = new StringTokenizer("");
		}

	}

}
