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import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashSet;
import java.util.Set;

public class B472 {

	private static boolean home = !"true".equals(System.getProperty("ONLINE_JUDGE"));
	private static boolean debug = false;
	
	public static void main(String[] args) throws IOException {
		int nrTeste = 3;
String[] inputs = {"5 8\n.#.#..#.\n.....#..\n.#.#..#.\n#.#....#\n.....#..\n", "5 5\n..#..\n..#..\n#####\n..#..\n..#..\n", "5 9\n........#\n#........\n..##.#...\n.......#.\n....#.#.#\n"};
String[] expected = {"Yes\n", "No\n", "No\n"};
		for (int i = 0; home && i < nrTeste; i++) {
			System.out.print("\nExpect: " + expected[i] + "\n   Got: ");
			System.setIn(new ByteArrayInputStream(inputs[i].getBytes()));
			solve();
		}
		if (!home) {
			solve();
		}
		System.out.close();
	}
	
	public static void solve() throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(System.out);
		String[] line;
		line = br.readLine().split(" ");
		int n = Integer.parseInt(line[0]);
		int m = Integer.parseInt(line[1]);
		Set <String> lines = new HashSet<>();
		for (int i = 0; i < n; i++) {
			lines.add(br.readLine());
		}
		boolean yes = true;
		for (int i = 0; i < m; i++) {
			int count = 0;
			for (String s : lines) {
				if (s.charAt(i) == '#') {
					count++;
				}
			}
			if (count > 1) {
				yes = false;
				break;
			}
		}
		if (yes) {
			pw.println("Yes");
		} else {
			pw.println("No");
		}
		br.close();
		pw.flush();
	}
	
}
