
import java.util.Scanner;

public class Main {
	public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	}
	//一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	}

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	}
	//一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	}

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	}

} Main public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	} PrintChess {
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	} for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		} int i=1; int i=1; i 1 i<H+1 i H+1 H 1 i++ i++ i {
			PrintLine(i, W);
		} {
			PrintLine(i, W);
		} PrintLine(i, W) PrintLine i W int H H int W W //一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	} PrintLine {
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	} if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		} lineCounter%2==0 lineCounter%2 lineCounter 2 0 {
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		} for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			} int i=1; int i=1; i 1 i<W+1 i W+1 W 1 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 "." {
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		} for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			} int i=1; int i=1; i 1 i<W+1 i W+1 W 1 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 lineCounter lineCounter int W W public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	} main {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	} Scanner scanner=new Scanner(System.in); scanner new Scanner(System.in) int H; H int W; W H=scanner.nextInt() H scanner.nextInt() scanner.nextInt scanner W=scanner.nextInt() W scanner.nextInt() scanner.nextInt scanner while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		} H!=0&&W!=0 H!=0 H 0 W!=0 W 0 {
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		} PrintChess(H, W) PrintChess H W System.out.println("") System.out.println System.out System System.out "" H=scanner.nextInt() H scanner.nextInt() scanner.nextInt scanner W=scanner.nextInt() W scanner.nextInt() scanner.nextInt scanner scanner.close() scanner.close scanner String[] args args public class Main {
	public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	}
	//一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	}

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	}

} public class Main {
	public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	}
	//一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	}

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	}

} Main

import java.util.Scanner;

public class Main {
	public static void PrintChess(int H,int W){
		for(int i=1;i<H+1;i++){
			PrintLine(i, W);
		}
	}
	//一行出力メソッド
	public static void PrintLine(int lineCounter,int W){
		//引数はラインカウンタと高さ
		if(lineCounter%2==0){
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print("#");
				}else{
					System.out.print(".");
				}
			}
		}else{
			for(int i=1;i<W+1;i++){
				if(i%2==0){
					System.out.print(".");
				}else{
					System.out.print("#");
				}
			}
			
		}
		System.out.println("");
	}

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int H;
		int W;
		//最初の値を格納
		H=scanner.nextInt();
		W=scanner.nextInt();
		while(H!=0&&W!=0){
			PrintChess(H, W);
			
			System.out.println("");
			H=scanner.nextInt();
			W=scanner.nextInt();
		}
		scanner.close();
		//System.out.println("exit");
	}

}