import java.io.*;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        int h = in.nextInt();
        int w = in.nextInt();
        char[][] grid = new char[h][w];
        int[] dx = {-1, 1, 0, 0};
        int[] dy = {0, 0, -1, 1};
        for (int i=0; i<h; i++) {
            grid[i] = in.nextCharArray(w);
        }
        for (int i=0; i<h; i++) {
            for (int j=0; j<w; j++) {
                if (grid[i][j] == '#') {
                    boolean containsHashMark = false;
                    for (int k=0; k<4; k++) {
                        if (i + dx[k] >= 0 && i + dx[k] <= h - 1 &&
                            j + dy[k] >= 0 && j + dy[k] <= w - 1) {
                            if (grid[i + dx[k]][j + dy[k]] == '#') {
                                containsHashMark = true;
                            }
                        }
                    }
                    if (!containsHashMark) {
                        out.println("No");
                        out.close();
                        return;
                    }
                }
            }
        }
        out.println("Yes");
        out.close();
        //INT OVERFLOW -> USE LONG
        //ARR OUT OF BOUNDS
    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public Scanner(String s) {
            try {
                br = new BufferedReader(new FileReader(s));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

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

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

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

        public double[] nextDoubleArray(int n) {
            double[] arr = new double[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextDouble();
            }
            return arr;
        }

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

        public char[] nextCharArray(int n) {
            char[] arr = nextLine().trim().replaceAll("\\s", "").toCharArray();
            return arr;
        }

        public String[] nextStringArray(int n) {
            String[] arr = new String[n];
            for (int i = 0; i < n; i++) {
                arr[i] = next();
            }
            return arr;
        }
    }
}


Measured memory_bytes: 23380