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

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    }
} import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    }
} Main public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String line = br.readLine(); line br.readLine() br.readLine br while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        } !(line.equals("0 0")) (line.equals("0 0")) line.equals line "0 0" {
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        } String[] input = line.split(" "); input line.split(" ") line.split line " " int h = Integer.valueOf(input[0]); h Integer.valueOf(input[0]) Integer.valueOf Integer input[0] input 0 int w = Integer.valueOf(input[1]); w Integer.valueOf(input[1]) Integer.valueOf Integer input[1] input 1 StringBuilder sb = new StringBuilder(); sb new StringBuilder() for(int i = 0; i < h; i++){
                boolean which = i%2 == 0;
                for(int j = 0; j < w; j++){
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                }
                sb.append("\n");
            } int i = 0; int i = 0; i 0 i < h i h i++ i++ i {
                boolean which = i%2 == 0;
                for(int j = 0; j < w; j++){
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                }
                sb.append("\n");
            } {
                boolean which = i%2 == 0;
                for(int j = 0; j < w; j++){
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                }
                sb.append("\n");
            } boolean which = i%2 == 0; which i%2 == 0 i%2 i 2 0 for(int j = 0; j < w; j++){
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                } int j = 0; int j = 0; j 0 j < w j w j++ j++ j {
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                } {
                    if(which) sb.append("#");
                    else sb.append(".");
                    which = !which;
                } if(which) sb.append("#");
                    else sb.append("."); which sb.append("#") sb.append sb "#" sb.append(".") sb.append sb "." which = !which which !which which sb.append("\n") sb.append sb "\n" System.out.println(sb) System.out.println System.out System System.out sb line = br.readLine() line br.readLine() br.readLine br String[] args args public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    }
} public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

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

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();

        while(!(line.equals("0 0"))){
            String[] input = line.split(" ");
            int h = Integer.valueOf(input[0]);
            int w = Integer.valueOf(input[1]);
            StringBuilder sb = new StringBuilder();

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

            System.out.println(sb);
            
            line = br.readLine();
        }

    }
}