import java.util.Scanner;
import java.lang.Math;
public class Main{
    public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    }
    public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    }
    public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    }
} import java.util.Scanner; Scanner java.util import java.lang.Math; Math java.lang public class Main{
    public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    }
    public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    }
    public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    }
} Main public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    } main {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	} scan.hasNext() scan.hasNext scan {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	} String input = scan.nextLine(); input scan.nextLine() scan.nextLine scan String[] inputs = input.split(" "); inputs input.split(" ") input.split input " " int height = Integer.parseInt(inputs[0]); height Integer.parseInt(inputs[0]) Integer.parseInt Integer inputs[0] inputs 0 int width = Integer.parseInt(inputs[1]); width Integer.parseInt(inputs[1]) Integer.parseInt Integer inputs[1] inputs 1 if (height == 0 && width == 0) {
		break;
	    } height == 0 && width == 0 height == 0 height 0 width == 0 width 0 {
		break;
	    } break; int line = 0; line 0 while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    } line < height line height {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    } if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		} line % 2 == 0 line % 2 line 2 0 {
		    printcheck1(width);
		} printcheck1(width) printcheck1 width {
		    printcheck2(width);
		} printcheck2(width) printcheck2 width line++ line System.out.println() System.out.println System.out System System.out String[] args args public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    } printcheck1 {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    } for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	} int i = 0; int i = 0; i 0 i < width i width i++ i++ i {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	} {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	} if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    } i % 2 == 0 i % 2 i 2 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 int width width public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    } printcheck2 {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    } for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	} int i = 0; int i = 0; i 0 i < width i width i++ i++ i {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	} {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	} if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    } i % 2 == 0 i % 2 i 2 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 int width width public class Main{
    public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    }
    public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    }
    public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    }
} public class Main{
    public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    }
    public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    }
    public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    }
} Main
import java.util.Scanner;
import java.lang.Math;
public class Main{
    public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	while (scan.hasNext()) {
	    String input = scan.nextLine();
	    String[] inputs = input.split(" ");
	    int height = Integer.parseInt(inputs[0]);
	    int width = Integer.parseInt(inputs[1]);
	    if (height == 0 && width == 0) {
		break;
	    }
	    int line = 0;
	    while(line < height) {
		if (line % 2 == 0) {
		    printcheck1(width);
		} else {
		    printcheck2(width);
		}
		line++;
	    }
	    System.out.println();
	}
    }
    public static void printcheck1(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print("#");
	    } else {
		System.out.print(".");
	    }
	}
	System.out.println();
    }
    public static void printcheck2(int width) {
	for (int i = 0; i < width; i++) {
	    if (i % 2 == 0) {
		System.out.print(".");
	    } else {
		System.out.print("#");
	    }
	}
	System.out.println();
    }
}