import java.util.Scanner;class Main {
    public void yatary(){
        Scanner sc = new Scanner(System.in);
        int H = 0,W = 0;
        int x,y,a,b;
        H = sc.nextInt();
        W = sc.nextInt();
          while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        }
    }
    public static void main(String[] args) { 
        new Main().yatary();
    } 
} import java.util.Scanner; Scanner java.util class Main {
    public void yatary(){
        Scanner sc = new Scanner(System.in);
        int H = 0,W = 0;
        int x,y,a,b;
        H = sc.nextInt();
        W = sc.nextInt();
          while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        }
    }
    public static void main(String[] args) { 
        new Main().yatary();
    } 
} Main public void yatary(){
        Scanner sc = new Scanner(System.in);
        int H = 0,W = 0;
        int x,y,a,b;
        H = sc.nextInt();
        W = sc.nextInt();
          while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        }
    } yatary {
        Scanner sc = new Scanner(System.in);
        int H = 0,W = 0;
        int x,y,a,b;
        H = sc.nextInt();
        W = sc.nextInt();
          while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int H = 0 H 0 W = 0; W 0 int x x y y a a b; b H = sc.nextInt() H sc.nextInt() sc.nextInt sc W = sc.nextInt() W sc.nextInt() sc.nextInt sc while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        } H != 0 || W != 0 H != 0 H 0 W != 0 W 0 {
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        } for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              } x = 1; x = 1 x 1 x <= H x H x++ x++ x { 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              } { 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              } for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  } y = 1; y = 1 y 1 y <= W y W y++ y++ y {
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  } {
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  } a = x % 2 a x % 2 x 2 b = y % 2 b y % 2 y 2 if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } b == 1 b 1 {
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      } if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      } a == 1 a 1 {
                          System.out.print("#");
                      } System.out.print("#") System.out.print System.out System System.out "#" {
                          System.out.print(".");
                      } System.out.print(".") System.out.print System.out System System.out "." if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } a == 0 a 0 {
                          System.out.print("#"); 
                      } System.out.print("#") System.out.print System.out System System.out "#" {    
                          System.out.print(".");   
                      } System.out.print(".") System.out.print System.out System System.out "." System.out.println() System.out.println System.out System System.out System.out.println() System.out.println System.out System System.out H = sc.nextInt() H sc.nextInt() sc.nextInt sc W = sc.nextInt() W sc.nextInt() sc.nextInt sc public static void main(String[] args) { 
        new Main().yatary();
    } main { 
        new Main().yatary();
    } new Main().yatary() new Main().yatary new Main() String[] args args
import java.util.Scanner;class Main {
    public void yatary(){
        Scanner sc = new Scanner(System.in);
        int H = 0,W = 0;
        int x,y,a,b;
        H = sc.nextInt();
        W = sc.nextInt();
          while(H != 0 || W != 0){
              for(x = 1; x <= H;x++){ 
                  for(y = 1; y <= W;y++){
                      a = x % 2;
                      b = y % 2;
                      if(b == 1){
                      if(a == 1){
                          System.out.print("#");
                      }else{
                          System.out.print(".");
                      }
                      }else if(a == 0){
                          System.out.print("#"); 
                      }else{    
                          System.out.print(".");   
                      } 
                  }
        System.out.println();          
              }
        System.out.println();
        H = sc.nextInt();
        W = sc.nextInt();
        }
    }
    public static void main(String[] args) { 
        new Main().yatary();
    } 
}