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

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