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

public class Main{
  
    
    public static void main(String[] args) throws IOException {
        FastScanner sc = new FastScanner(System.in);
        int n=sc.nextInt();
        int m=sc.nextInt();
        if(n==1 || m==1){
            System.out.println("Yes");
            return;
        }
        
        String s[]=new String[n];
        for(int i=0;i<n;i++){
            s[i]=sc.next();
            
        }
        for(int i=0;i<n;i++){
            for(int j=i+1;j<n;j++){
                if(!can(s[i],s[j])){
                    System.out.println("No");
                    return;
                }
            }
        }
        System.out.println("Yes");
    }
    public static boolean can(String s1,String s2){
        if(s1.equals(s2)){
            return true;
        }
        for(int i=0;i<s1.length();i++){
            if(s1.charAt(i)=='#' && s2.charAt(i)=='#')return false;
        
        }
        return true;
    }
    

    static class FastScanner {

        BufferedReader br;
        StringTokenizer st;

        public FastScanner(InputStream i) {
            br = new BufferedReader(new InputStreamReader(i));
            st = new StringTokenizer("");
        }
        public String next() throws IOException {
            if (st.hasMoreTokens()) {
                return st.nextToken();
            } else {
                st = new StringTokenizer(br.readLine());
            }
            return next();
        }

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

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

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