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

public class Main {
    public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    }
    public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    }
    public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    }
} Main public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    } main {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    } BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); reader new BufferedReader(new InputStreamReader(System.in)) StringBuilder builder = new StringBuilder(); builder new StringBuilder() String check = "#"; check "#" String period = "."; period "." while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        } true {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        } String line = reader.readLine(); line reader.readLine() reader.readLine reader String[] columns = line.split(" "); columns line.split(" ") line.split line " " int y = Integer.parseInt(columns[0]); y Integer.parseInt(columns[0]) Integer.parseInt Integer columns[0] columns 0 int x = Integer.parseInt(columns[1]); x Integer.parseInt(columns[1]) Integer.parseInt Integer columns[1] columns 1 if (x == 0 && y == 0 ) 
                break; x == 0 && y == 0 x == 0 x 0 y == 0 y 0 break; for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            } int j = 0 ; int j = 0 ; j 0 j < y j y j++ j++ j {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            } {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            } if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x)); j % 2 == 0 j % 2 j 2 0 builder.append(DrawChessBoard(check,period,x)) builder.append builder DrawChessBoard(check,period,x) DrawChessBoard check period x builder.append(DrawChessBoard(period,check,x)) builder.append builder DrawChessBoard(period,check,x) DrawChessBoard period check x builder.append("\n") builder.append builder "\n" System.out.print(builder) System.out.print System.out System System.out builder String[] args args public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    } DrawChessBoard {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    } StringBuilder str = new StringBuilder(); str new StringBuilder() for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            } int i = 0 ; int i = 0 ; i 0 i < x i x i++ i++ i {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            } {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            } if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period); i % 2 == 0 i % 2 i 2 0 str.append(check) str.append str check str.append(period) str.append str period str.append("\n") str.append str "\n" return str; str String check check String period period int x x public class Main {
    public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    }
    public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    }
} public class Main {
    public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    }
    public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    }
} Main

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

public class Main {
    public static void main (String[] args ) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder builder = new StringBuilder();
        String check = "#";
        String period = ".";
        
        while(true) {
            String line = reader.readLine();
            String[] columns = line.split(" ");
            int y = Integer.parseInt(columns[0]);
            int x = Integer.parseInt(columns[1]);
            
            if (x == 0 && y == 0 ) 
                break;
            for ( int j = 0 ; j < y ; j++) {
                if (j % 2 == 0 )
                    builder.append(DrawChessBoard(check,period,x));
                else
                    builder.append(DrawChessBoard(period,check,x));
            }
            builder.append("\n");
        }
        System.out.print(builder);
    }
    public static StringBuilder DrawChessBoard(String check,String period,int x) {
        StringBuilder str = new StringBuilder();
        for ( int i = 0 ; i < x ; i++) {
                if (i % 2 == 0 ) 
                    str.append(check);
                else
                    str.append(period);
            }
            str.append("\n");
            return str;
    }
}