import java.util.*;
 
class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int H, W;
     
    while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    }
  }
} import java.util.*; util.* java class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int H, W;
     
    while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    }
  }
} Main public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int H, W;
     
    while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    }
  } main {
    Scanner in = new Scanner(System.in);
    int H, W;
     
    while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    }
  } Scanner in = new Scanner(System.in); in new Scanner(System.in) int H H W; W while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    } in.hasNext() in.hasNext in {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    } StringBuilder odd  = new StringBuilder(); odd new StringBuilder() StringBuilder even = new StringBuilder(); even new StringBuilder() StringBuilder total = new StringBuilder(); total new StringBuilder() String crlf = System.getProperty("line.separator"); crlf System.getProperty("line.separator") System.getProperty System "line.separator" H = in.nextInt() H in.nextInt() in.nextInt in W = in.nextInt() W in.nextInt() in.nextInt in if(H == 0 && W == 0) break; H == 0 && W == 0 H == 0 H 0 W == 0 W 0 break; for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      } int w = 0; int w = 0; w 0 w < W w W w++ w++ w {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      } {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      } if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        } w % 2 == 1 w % 2 w 2 1 { 
          odd.append("#");
          even.append(".");
        } odd.append("#") odd.append odd "#" even.append(".") even.append even "." {
          odd.append(".");
          even.append("#");
        } odd.append(".") odd.append odd "." even.append("#") even.append even "#" odd.append(crlf) odd.append odd crlf even.append(crlf) even.append even crlf for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      } int h = 0; int h = 0; h 0 h < H h H h++ h++ h {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      } {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      } if (h % 2 == 1) total.append(odd);
        else            total.append(even); h % 2 == 1 h % 2 h 2 1 total.append(odd) total.append total odd total.append(even) total.append total even System.out.println(total.toString()) System.out.println System.out System System.out total.toString() total.toString total String[] args args
import java.util.*;
 
class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int H, W;
     
    while (in.hasNext()) {
      StringBuilder odd  = new StringBuilder();
      StringBuilder even = new StringBuilder();
      StringBuilder total = new StringBuilder();
      String crlf = System.getProperty("line.separator");
      H = in.nextInt();
      W = in.nextInt();
      if(H == 0 && W == 0) break;
       
      for (int w = 0; w < W; w++) {
        if (w % 2 == 1) { 
          odd.append("#");
          even.append(".");
        } else {
          odd.append(".");
          even.append("#");
        }
      }
      odd.append(crlf);
      even.append(crlf);
       
      for (int h = 0; h < H; h++) {
        if (h % 2 == 1) total.append(odd);
        else            total.append(even);
      }
      System.out.println(total.toString());
    }
  }
}