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