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

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Abhilash
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            char arr[][] = new char[n][m];
            for (int i = 0; i < n; i++) {
                String s = in.next();
                for (int j = 0; j < m; j++) {
                    arr[i][j] = s.charAt(j);
                }
            }
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    boolean flag = false;
                    if (arr[i][j] == '#') {
                        if (i + 1 < n && arr[i + 1][j] == '#')
                            flag = true;
                        if (i - 1 > -1 && arr[i - 1][j] == '#')
                            flag = true;
                        if (j + 1 < n && arr[i][j + 1] == '#')
                            flag = true;
                        if (j - 1 > -1 && arr[i][j - 1] == '#')
                            flag = true;
                    } else {
                        flag = true;
                    }
                    if (!flag) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

    }
}

