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import java.io.*;
import java.util.Locale;
import java.util.StringTokenizer;

public class C implements Runnable {

  private static final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;

  private BufferedReader in;
  private PrintWriter out;
  private StringTokenizer tok = new StringTokenizer("");

  private void init() throws FileNotFoundException {
    Locale.setDefault(Locale.US);
    String fileName = "";
    if (ONLINE_JUDGE) {
      in = new BufferedReader(new InputStreamReader(System.in));
      out = new PrintWriter(System.out);
    } else {
      in = new BufferedReader(new FileReader("input.txt"));
      out = new PrintWriter("output.txt");
    }
  }

  String readString() {
    while (!tok.hasMoreTokens()) {
      try {
        tok = new StringTokenizer(in.readLine());
      } catch (Exception e) {
        return null;
      }
    }
    return tok.nextToken();
  }

  int readInt() {
    return Integer.parseInt(readString());
  }

  long readLong() {
    return Long.parseLong(readString());
  }

  double readDouble() {
    return Double.parseDouble(readString());
  }

  int[] readIntArray(int size) {
    int[] a = new int[size];
    for (int i = 0; i < size; i++) {
      a[i] = readInt();
    }
    return a;
  }

  public static void main(String[] args) {
    //new Thread(null, new _Solution(), "", 128 * (1L << 20)).start();
    new C().run();
  }

  long timeBegin, timeEnd;

  void time() {
    timeEnd = System.currentTimeMillis();
    // System.err.println("Time = " + (timeEnd - timeBegin));
  }

  @Override
  public void run() {
    try {
      timeBegin = System.currentTimeMillis();
      init();
      solve();
      out.close();
      time();
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(-1);
    }
  }

  private int aiverson(boolean good) {
    return good ? 1 : 0;
  }

  static final long MOD = 1_000_000_007;

  static final int MAX = 1000_000 + 1;

  private void solve() throws IOException {
    int n = readInt();
    int m = readInt();
    char[][] matrix = new char[n][m];
    for (int i = 0; i < n; i++) {
      matrix[i] = readString().toCharArray();
    }

    long[] numbers = new long[n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        numbers[i] <<= 1L;
        numbers[i] += matrix[i][j] == '.' ? 0 : 1;
      }
    }
    for (int i = 0; i < n; i++) {
      for (int j = i + 1; j < n; j++) {
        long sum = numbers[i] & numbers[j];
        if(!(sum == 0 || sum == numbers[i] && sum == numbers[j])){
          out.print("No");
          return;
        }
      }
    }
    out.print("Yes");

  }


}
