import java.util.Scanner;

class Main{
	public static void main(String[] args) 	{
		Scanner sc = new Scanner(System.in);
		while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		}
		sc.close();
	}	
} import java.util.Scanner; Scanner java.util class Main{
	public static void main(String[] args) 	{
		Scanner sc = new Scanner(System.in);
		while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		}
		sc.close();
	}	
} Main public static void main(String[] args) 	{
		Scanner sc = new Scanner(System.in);
		while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		}
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		}
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		} 0 < 1 0 1 {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		} int tate = sc.nextInt(); tate sc.nextInt() sc.nextInt sc int yoko = sc.nextInt(); yoko sc.nextInt() sc.nextInt sc if(tate == 0 && yoko == 0) break; tate == 0 && yoko == 0 tate == 0 tate 0 yoko == 0 yoko 0 break; for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			} int i = 0 ; int i = 0 ; i 0 i < tate i tate i++ i++ i {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			} {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			} if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				} i % 2 == 0 i % 2 i 2 0 {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				} for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					} int j = 0 ; int j = 0 ; j 0 j < yoko j yoko j++ j++ j {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					} {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					} if(j % 2 == 0) System.out.printf("#");
						else System.out.printf("."); j % 2 == 0 j % 2 j 2 0 System.out.printf("#") System.out.printf System.out System System.out "#" System.out.printf(".") System.out.printf System.out System System.out "." System.out.printf("\n") System.out.printf System.out System System.out "\n" {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				} for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					} int j = 0 ; int j = 0 ; j 0 j < yoko j yoko j++ j++ j {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					} {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					} if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#"); j % 2 == 0 j % 2 j 2 0 System.out.printf(".") System.out.printf System.out System System.out "." System.out.printf("#") System.out.printf System.out System System.out "#" System.out.printf("\n") System.out.printf System.out System System.out "\n" System.out.printf("\n") System.out.printf System.out System System.out "\n" sc.close() sc.close sc String[] args args
import java.util.Scanner;

class Main{
	public static void main(String[] args) 	{
		Scanner sc = new Scanner(System.in);
		while(0 < 1) {
			int tate = sc.nextInt();
			int yoko = sc.nextInt();
			if(tate == 0 && yoko == 0) break;
			for(int i = 0 ; i < tate ; i++ ) {
				if(i % 2 == 0) {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf("#");
						else System.out.printf(".");
					}
					System.out.printf("\n");
				}
				else {
					for(int j = 0 ; j < yoko ; j++) {
						if(j % 2 == 0) System.out.printf(".");
						else System.out.printf("#");
					}
					System.out.printf("\n");
				}
			}
			System.out.printf("\n");
		}
		sc.close();
	}	
}
