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import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Rene
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskB solver = new TaskB();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskB {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            long[] x = new long[n];
            boolean ok = true;
            for (int i = 0; i < n; i++) {
                String s = in.next();
                s = s.replace('.', '0').replace('#', '1');
                x[i] = Long.parseLong(s, 2);
                for (int j = 0; j < i; j++) {
                    if ((x[i] & x[j]) != 0 && x[i] != x[j]) ok = false;
                }
            }
            out.println(ok ? "Yes" : "No");
        }

    }

    static interface InputInterface {
    }

    static class InputReader implements InputInterface {
        public InputStream stream;
        private int current;
        private int size;
        private byte[] buffer = new byte[10000];

        public InputReader(InputStream stream) {
            this.stream = stream;
            current = 0;
            size = 0;
        }

        public InputReader() {
        }


        public String next() {
            StringBuilder sb = new StringBuilder();
            int c = readNextValid();
            while (!isEmpty(c)) {
                sb.append((char) c);
                c = read();
            }
            return sb.toString();
        }

        int read() {
            int result;
            try {
                if (current >= size) {
                    current = 0;
                    size = stream.read(buffer);
                    if (size < 0) return -1;
                }
            } catch (IOException e) {
                throw new RuntimeException();
            }
            return buffer[current++];
        }


        public int nextInt() {
            int sign = 1;
            int result = 0;
            int c = readNextValid();
            if (c == '-') {
                sign = -1;
                c = read();
            }
            do {
                if (c < '0' || c > '9') throw new RuntimeException();
                result = 10 * result + c - '0';
                c = read();
            } while (!isEmpty(c));
            result *= sign;
            return result;
        }

        private int readNextValid() {
            int result;
            do {
                result = read();
            } while (isEmpty(result));
            return result;
        }

        private boolean isEmpty(int c) {
            return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == -1;
        }

    }
}

