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

public class Main{
	
	public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main{
	
	public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	}
} Main public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	} 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().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		} true {
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		} String[] line = br.readLine().split(" "); line br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int h = Integer.parseInt(line[0]); h Integer.parseInt(line[0]) Integer.parseInt Integer line[0] line 0 int w = Integer.parseInt(line[1]); w Integer.parseInt(line[1]) Integer.parseInt Integer line[1] line 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 sb.delete(0,sb.length()) sb.delete sb 0 sb.length() sb.length sb String[] args args public class Main{
	
	public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	}
} public class Main{
	
	public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	}
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main{
	
	public static void main(String[] args)throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		while(true){
			String[] line = br.readLine().split(" ");
			
			int h = Integer.parseInt(line[0]);
			int w = Integer.parseInt(line[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);
			sb.delete(0,sb.length());
		}
	}
}