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

public class Main {
  static InputReader in;
  static PrintWriter out;

  static class Solution {
    void solve() throws IOException {
      while (true) {
        int H = in.nextInt();
        int W = in.nextInt();
        if (H == 0 && W == 0) break;
        
        for (int i = 0; i < H; i++) {
          if (i % 2 == 0) {
            for (int j = 0; j < W; j++) {
              if (j % 2 == 0) {
                out.print("#");
              } else {
                out.print(".");
              }
            }
            out.print("\n");
          } else {
            if (i % 2 == 0) {
              for (int j = 0; j < W; j++) {
                if (j % 2 == 1) {
                  out.print("#");
                } else {
                  out.print(".");
                }
              }
            } 
            out.print("\n");
          }
        } 
        out.print("\n");
      }
    }
}

  public static void main(String[] args) throws IOException {
    in = new InputReader(System.in);
    out = new PrintWriter(System.out);
    Solution solver = new Solution();
    solver.solve();
    out.close();
}

  static class InputReader {
    public BufferedReader br;
    public StringTokenizer st;

    public InputReader(InputStream stream) {
      br = new BufferedReader(new InputStreamReader(stream));
    }

    public int nextInt() throws IOException {
      while (st == null || !st.hasMoreTokens()) {
        st = new StringTokenizer(br.readLine());
      }
      return Integer.parseInt(st.nextToken());
    }

    public long nextLong() throws IOException {
      while (st == null || !st.hasMoreTokens()) {
        st = new StringTokenizer(br.readLine());
      }
      return Long.parseLong(st.nextToken());
    }

    public String next() throws IOException {
      while (st == null || !st.hasMoreTokens()) {
        st = new StringTokenizer(br.readLine());
      }
      return st.nextToken();
    }

    public double nextDouble() throws IOException {
      while (st == null || !st.hasMoreTokens()) {
        st = new StringTokenizer(br.readLine());
      }
      return Double.parseDouble(st.nextToken());
    }

  }

}