#include <iostream>
#include <string>
using namespace std;

int main() {
	int H, W, x;
	string a[300];
	string b[300];
	cin >> H >> W;
	while(!(H == 0 && W == 0)){
		for (int i = 0; i < 150; i++) {
			a[i * 2] = "#";
			a[i * 2 + 1] = ".";
			b[i * 2] = ".";
			b[i * 2 + 1] = "#";
		}
		a[300] = "#";
		b[300] = ".";
		x = H / 2;
		for (int j = 0; j < x; j++) {
			for (int k = 0; k < W; k++) {
				cout << a[k];
			}
			cout << "\n";
			for (int l = 0; l < W; l++) {
				cout << b[l];
			}
			cout << "\n";
		}
		if (W % 2 == 1) {
			for (int m = 0; m < W; m++) {
				cout << a[m];
			}
			cout << "\n";
			cin >> H >> W;
		}
	return 0;
	}