import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(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 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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(j % 2 == 0){
							sb.append(".");
						}else{
							sb.append("#");
						}
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		} true {

			String[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(j % 2 == 0){
							sb.append(".");
						}else{
							sb.append("#");
						}
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		} String[] token = br.readLine().split(" "); token br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int h = Integer.parseInt(token[0]); h Integer.parseInt(token[0]) Integer.parseInt Integer token[0] token 0 int w = Integer.parseInt(token[1]); w Integer.parseInt(token[1]) Integer.parseInt Integer token[1] token 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(".");
						}
					}else{
						if(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){
						if(j % 2 == 0){
							sb.append("#");
						}else{
							sb.append(".");
						}
					}else{
						if(j % 2 == 0){
							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(".");
						}
					}else{
						if(j % 2 == 0){
							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(".");
						}
					}else{
						if(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){
						if(j % 2 == 0){
							sb.append("#");
						}else{
							sb.append(".");
						}
					}else{
						if(j % 2 == 0){
							sb.append(".");
						}else{
							sb.append("#");
						}
					}
				} {
					if(i % 2 == 0){
						if(j % 2 == 0){
							sb.append("#");
						}else{
							sb.append(".");
						}
					}else{
						if(j % 2 == 0){
							sb.append(".");
						}else{
							sb.append("#");
						}
					}
				} if(i % 2 == 0){
						if(j % 2 == 0){
							sb.append("#");
						}else{
							sb.append(".");
						}
					}else{
						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(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 "#" 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
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

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[] token = br.readLine().split(" ");
			int h = Integer.parseInt(token[0]);
			int w = Integer.parseInt(token[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(".");
						}
					}else{
						if(j % 2 == 0){
							sb.append(".");
						}else{
							sb.append("#");
						}
					}
				}
				sb.append("\n");
			}
			sb.append("\n");
		}

		System.out.print(sb);

	}
}