import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

    static BufferedReader in;
    static PrintWriter out;
    static StringTokenizer tok;

    void solve() throws IOException {
        int h = ni();
        int w = ni();
        String[] s = nsa(h);

        boolean[][] used = new boolean[h][w];
        for (int i = 0; i < h; i++) {
            outside:
            for (int j = 0; j < w; j++) {
                if (i == 0 && j == 0) {
                    continue;
                }

                for (int k = 0; k < h; k++) {
                    Arrays.fill(used[k], false);
                }

                for (int k = 0; k < h; k++) {
                    for (int l = 0; l < w; l++) {
                        if (s[k].charAt(l) == '#' && !used[k][l]) {
                            if (k + i > h - 1 || l + j > w - 1) {
                                continue outside;
                            }
                            if (s[k + i].charAt(l + j) == '.' || used[k + i][l + j]) {
                                continue outside;
                            }
                            used[k + i][l + j] = true;
                        }
                    }
                }

                out.println("YES");
                return;
            }
        }

        out.println("NO");
    }

    String ns() throws IOException {
        while (!tok.hasMoreTokens()) {
            tok = new StringTokenizer(in.readLine(), " ");
        }
        return tok.nextToken();
    }

    int ni() throws IOException {
        return Integer.parseInt(ns());
    }

    long nl() throws IOException {
        return Long.parseLong(ns());
    }

    double nd() throws IOException {
        return Double.parseDouble(ns());
    }

    String[] nsa(int n) throws IOException {
        String[] res = new String[n];
        for (int i = 0; i < n; i++) {
            res[i] = ns();
        }
        return res;
    }

    int[] nia(int n) throws IOException {
        int[] res = new int[n];
        for (int i = 0; i < n; i++) {
            res[i] = ni();
        }
        return res;
    }

    long[] nla(int n) throws IOException {
        long[] res = new long[n];
        for (int i = 0; i < n; i++) {
            res[i] = nl();
        }
        return res;
    }

    public static void main(String[] args) throws IOException {
        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
        tok = new StringTokenizer("");
        Main main = new Main();
        main.solve();
        out.close();
    }
}