using System;

class Test {
    static void Main() {
        string[] str = Console.ReadLine().Split();
        int h = int.Parse(str[0]);
        int w = int.Parse(str[1]);
        string[] s = new string[h];
        bool black = false;
        string ans = "Yes";

        for (int i = 0; i < h; i++) {
            s[i] = Console.ReadLine();
        }
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                Console.WriteLine("ok,{0}", ans);
                if (s[i][j] == '#') {
                    black = true;
                    if (i + 1 < h) {
                        if (j + 1 < w) {
                            if (s[i + 1][j] != '#' && s[i][j + 1] != '#') ans = "No";
                        } /*else {
                            if (s[i + 1][j] != '#') ans = "No";
                        }*/
                    } /*else {
                        if (j + 1 < w) {
                            if (s[i][j + 1] != '#') ans = "No";
                        } else {
                            ans = "No";
                        }
                    }*/
                }
            }
        }
        if (!black) ans = "No";
        Console.WriteLine(ans);
    }
}