/* ITP1_5_C */
import java.io.*;

class Main
{
  public static void main(String[] args) throws IOException
  {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringBuilder sb = new StringBuilder();

    while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    }
    // output
    System.out.print(sb);
  }
} import java.io.*; io.* java class Main
{
  public static void main(String[] args) throws IOException
  {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringBuilder sb = new StringBuilder();

    while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    }
    // output
    System.out.print(sb);
  }
} Main public static void main(String[] args) throws IOException
  {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringBuilder sb = new StringBuilder();

    while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    }
    // output
    System.out.print(sb);
  } main {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringBuilder sb = new StringBuilder();

    while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    }
    // output
    System.out.print(sb);
  } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb = new StringBuilder(); sb new StringBuilder() while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    } true {
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    } String str[] = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int height = Integer.parseInt(str[0]); height Integer.parseInt(str[0]) Integer.parseInt Integer str[0] str 0 int width = Integer.parseInt(str[1]); width Integer.parseInt(str[1]) Integer.parseInt Integer str[1] str 1 if(height == 0 && width == 0) break; height == 0 && width == 0 height == 0 height 0 width == 0 width 0 break; if(height > 300 || width > 300) break; height > 300 || width > 300 height > 300 height 300 width > 300 width 300 break; for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      } int i = 0; int i = 0; i 0 i < height i height i++ i++ i {
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      } {
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      } for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        } int j = 0; int j = 0; j 0 j < width j width j++ j++ j {
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        } {
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        } if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append("."); (i + j) % 2 == 0 (i + j) % 2 (i + j) i j 2 0 sb.append("#") sb.append sb "#" sb.append(".") sb.append sb "." sb.append("\n") sb.append sb "\n" sb.append("\n") sb.append sb "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args
/* ITP1_5_C */
import java.io.*;

class Main
{
  public static void main(String[] args) throws IOException
  {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringBuilder sb = new StringBuilder();

    while(true){
      // input
      String str[] = br.readLine().split(" ");
      int height = Integer.parseInt(str[0]);
      int width = Integer.parseInt(str[1]);
      //finish
      if(height == 0 && width == 0) break;
      if(height > 300 || width > 300) break;
      // drow
      for(int i = 0; i < height; i++){
        for(int j = 0; j < width; j++){
          if((i + j) % 2 == 0)
            sb.append("#");
          else
            sb.append(".");
        }
        sb.append("\n");
      }
      sb.append("\n");
    }
    // output
    System.out.print(sb);
  }
}