import java.util.Scanner;

public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    int H, W, i, j, k;

    H = sc.nextInt();
    W = sc.nextInt();


    for(i=0; i<H; i++){
      for(j=0; j<W; j++){
        if((i+j)%2==0) System.out.printf("#");
        else if((i+j)%2==1) System.out.printf(".");
      }
      System.out.printf("\n");
    }
  }
}

