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

/**
 * @author Don Li
 */
public class MysticalMosaic {
    void solve() {
        int n = in.nextInt(), m = in.nextInt();
        String[] rows = new String[n];
        for (int i = 0; i < n; i++) rows[i] = in.nextToken();
        
        Arrays.sort(rows);
        boolean[] used_cols = new boolean[m];
        for (int i = 0; i < n; ) {
            int j = i;
            while (j < n && rows[j].equals(rows[i])) j++;
            for (int k = 0; k < m; k++) {
                if (rows[i].charAt(k) == '#') {
                    if (used_cols[k]) {
                        out.println("No");
                        return;
                    } else {
                        used_cols[k] = true;
                    }
                }
            }
            i = j;
        }
        out.println("Yes");
    }
    
    public static void main(String[] args) {
        in = new FastScanner(new BufferedReader(new InputStreamReader(System.in)));
        out = new PrintWriter(System.out);
        new MysticalMosaic().solve();
        out.close();
    }
    
    static FastScanner in;
    static PrintWriter out;
    
    static class FastScanner {
        BufferedReader in;
        StringTokenizer st;
        
        public FastScanner(BufferedReader in) {
            this.in = in;
        }
        
        public String nextToken() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(in.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
        
        public int nextInt() {
            return Integer.parseInt(nextToken());
        }
        
        public long nextLong() {
            return Long.parseLong(nextToken());
        }
        
        public double nextDouble() {
            return Double.parseDouble(nextToken());
        }
    }
}
