import java.io.*;
public class Main{
	public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	}
} import java.io.*; io.* java public class Main{
	public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	}
} Main public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	} main {
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	} BufferedReader input=new BufferedReader(new InputStreamReader(System.in)); input new BufferedReader(new InputStreamReader(System.in)) StringBuilder sb=new StringBuilder(); sb new StringBuilder() while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	} true {
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	} String str=input.readLine(); str input.readLine() input.readLine input String[] arr=str.split(" "); arr str.split(" ") str.split str " " int h=Integer.parseInt(arr[0]); h Integer.parseInt(arr[0]) Integer.parseInt Integer arr[0] arr 0 int w=Integer.parseInt(arr[1]); w Integer.parseInt(arr[1]) Integer.parseInt Integer arr[1] arr 1 if(h==0&&w==0){
			break;
		} h==0&&w==0 h==0 h 0 w==0 w 0 {
			break;
		} break; for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		} int i=0; int i=0; i 0 i<h i h i++ i++ i {

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		} {

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		} for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			} int j=0; int j=0; j 0 j<w j w j++ j++ j {
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			} {
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			} if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					} i%2==0 i%2 i 2 0 {
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					} if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						} j%2==0 j%2 j 2 0 {
						sb.append("#");
					} sb.append("#") sb.append sb "#" {
						sb.append(".");
						} sb.append(".") sb.append sb "." if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				} i%2==1 i%2 i 2 1 {
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				} if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					} j%2==1 j%2 j 2 1 {
						sb.append("#");
					} sb.append("#") sb.append sb "#" {
						sb.append(".");
					} sb.append(".") sb.append sb "." sb.append("\n") sb.append sb "\n" sb.append("\n") sb.append sb "\n" System.out.print(sb) System.out.print System.out System System.out sb String[] args args public class Main{
	public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	}
} public class Main{
	public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	}
} Main
import java.io.*;
public class Main{
	public static void main(String[] args)throws Exception{
		BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb=new StringBuilder();
		while(true){
		String str=input.readLine();
		String[] arr=str.split(" ");
		int h=Integer.parseInt(arr[0]);	
		int w=Integer.parseInt(arr[1]);
		if(h==0&&w==0){
			break;
		}
	
		for(int i=0;i<h;i++){

			for(int j=0;j<w;j++){
				if(i%2==0){
					if(j%2==0){
						sb.append("#");
					}else{
						sb.append(".");
						}
					}

				if(i%2==1){
					if(j%2==1){
						sb.append("#");
					}else{
						sb.append(".");
					}
				}
			}
			
				sb.append("\n");
		}
			sb.append("\n");

	}
		
		
		
		System.out.print(sb);
	}
}