        #include <iostream>
     
        int main()  {
        	int W, H;
        	while (1) {
        	std::cin >> W >> H;
        	for (int i = 1; i =< H; i++) {
        		for (int j = 1; j =< W; j++) {
        			if (j%2 == 0) {
        				std::cout << ".";
        			} else {
        				std::cout << "#";
        			} 
        				std::cout <<endl;
        		}
        			std::cout <<endl;	
        	}
        	}
     
     
     
     
     
     
        	return 0;
        }
