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));
        StringBuilder sb = new StringBuilder();
        while (true){
            String line = br.readLine();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        System.out.print(sb);
    }
} 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));
        StringBuilder sb = new StringBuilder();
        while (true){
            String line = br.readLine();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        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();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        System.out.print(sb);
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        while (true){
            String line = br.readLine();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        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();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        } true {
            String line = br.readLine();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        } String line = br.readLine(); line br.readLine() br.readLine br String[] ln = line.split(" "); ln line.split(" ") line.split line " " int H = Integer.parseInt(ln[0]); H Integer.parseInt(ln[0]) Integer.parseInt Integer ln[0] ln 0 int W = Integer.parseInt(ln[1]); W Integer.parseInt(ln[1]) Integer.parseInt Integer ln[1] ln 1 if (H==0 && W==0) break; H==0 && W==0 H==0 H 0 W==0 W 0 break; for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            } int j=0; int j=0; j 0 j<H j H j++ j++ j {
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            } {
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            } if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                } j%2==0 j%2 j 2 0 {
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                } for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    } int i=0; int i=0; i 0 i<W i W i++ i++ i {
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    } {
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    } if (i%2==0) sb.append("#");
                        else sb.append("."); i%2==0 i%2 i 2 0 sb.append("#") sb.append sb "#" sb.append(".") sb.append sb "." {
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                } for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    } int i=0; int i=0; i 0 i<W i W i++ i++ i {
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    } {
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    } if (i%2==0) sb.append(".");
                        else sb.append("#"); i%2==0 i%2 i 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" StringBuilder k = new StringBuilder(100); k new StringBuilder(100) System.out.print(k) System.out.print System.out System System.out k 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();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        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();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        System.out.print(sb);
    }
} 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));
        StringBuilder sb = new StringBuilder();
        while (true){
            String line = br.readLine();
            String[] ln = line.split(" ");
            int H = Integer.parseInt(ln[0]);
            int W = Integer.parseInt(ln[1]);
            if (H==0 && W==0) break;
            for (int j=0; j<H; j++){
                if (j%2==0){
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append("#");
                        else sb.append(".");
                    }
                }else{
                    for (int i=0; i<W; i++){
                        if (i%2==0) sb.append(".");
                        else sb.append("#");
                    }
                }
                sb.append("\n");
            }
            sb.append("\n");
        }
        StringBuilder k = new StringBuilder(100);
        System.out.print(k);
        System.out.print(sb);
    }
}