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

public class Main
{
	static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                     InputStreamReader(System.in));
        }

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

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

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

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

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

	public static void main (String[] args)
	{
		FastReader reader = new FastReader();
		int n = reader.nextInt();
		int m = reader.nextInt();
		String[] input = new String[n];

		for (int i=0; i<n; i++)
			input[i] = reader.nextLine();

		boolean check = true;

		for (int i=0; i<n; i++)
		{
			for (int j=i+1; j<n; j++)
			{
				if (!input[i].equals(input[j]))
				{
					for (int k=0; k<m; k++)
					{
						if (input[i].charAt(k)=='#' && input[j].charAt(k)=='#')
							check = false;
					}
				}
			}
		}

		if (check)
			System.out.println ("Yes");
		else
			System.out.println ("No");

	}
}
