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