import java.util.Scanner;
class Main {
	
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		while(true){ 
		int H = scanner.nextInt();
		int W = scanner.nextInt();
		
		if ( H == 0 && W == 0 ){
			break;
			}
			else{
				int smallh;
				int smallw;
				
				for( smallh = 0; smallh < H; smallh++  ) {
					
					for( smallw = 0; smallw < W; smallw++ ) {
						if(smallh % 2 == 0 ){
							if(smallw % 2 == 0){
							System.out.print("#");
							}
							else{
							System.out.print(".");	
							}
						}
						else{
							if(smallw % 2 == 0){
							System.out.print(".");
							}
							else{
							System.out.print("#");
							}
						}
				
						/*if(smallh % 2 == 1 && smallw % 2 == 0){
						System.out.print(".");
						}else{
							System.out.print("#");		
						}
						*/					
				 }
				 System.out.println();
			}	
		}
		System.out.println();
		}
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz