import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	}
} Main public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	} main {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int h=sc.nextInt(); h sc.nextInt() sc.nextInt sc int w=sc.nextInt(); w sc.nextInt() sc.nextInt sc while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		} h!=0||w!=0 h!=0 h 0 w!=0 w 0 {
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		} StringBuilder sb1=new StringBuilder(""); sb1 new StringBuilder("") StringBuilder sb2=new StringBuilder(""); sb2 new StringBuilder("") for(int m=1;m<w;m+=2)sb1.append("#."); int m=1; int m=1; m 1 m<w m w m+=2 m+=2 m 2 sb1.append("#."); sb1.append("#.") sb1.append sb1 "#." for(int m=1;m<w;m+=2)sb2.append(".#"); int m=1; int m=1; m 1 m<w m w m+=2 m+=2 m 2 sb2.append(".#"); sb2.append(".#") sb2.append sb2 ".#" if(w%2==1){sb1.append("#");sb2.append(".");
			} w%2==1 w%2 w 2 1 {sb1.append("#");sb2.append(".");
			} sb1.append("#") sb1.append sb1 "#" sb2.append(".") sb2.append sb2 "." for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			} int n=1; int n=1; n 1 n<h n h n+=2 n+=2 n 2 {
				System.out.println(sb1);
				System.out.println(sb2);
			} {
				System.out.println(sb1);
				System.out.println(sb2);
			} System.out.println(sb1) System.out.println System.out System System.out sb1 System.out.println(sb2) System.out.println System.out System System.out sb2 if(h%2==1)System.out.println(sb1); h%2==1 h%2 h 2 1 System.out.println(sb1) System.out.println System.out System System.out sb1 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 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	}
} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int h=sc.nextInt();
		int w=sc.nextInt();
		while (h!=0||w!=0){
			StringBuilder sb1=new StringBuilder("");
			StringBuilder sb2=new StringBuilder("");
			for(int m=1;m<w;m+=2)sb1.append("#.");
			for(int m=1;m<w;m+=2)sb2.append(".#");
			if(w%2==1){sb1.append("#");sb2.append(".");
			}
			for(int n=1;n<h;n+=2){
				System.out.println(sb1);
				System.out.println(sb2);
			}
			if(h%2==1)System.out.println(sb1);
			System.out.println("");
			h=sc.nextInt();
			w=sc.nextInt();
		}
	}
}