using namespace std;


int main()
{
	int H[100], W[100], count,count1,odd;
	count = 0;
	count1 = 0;
	odd = 3;
	while (count < 300)
	{
		cin >> H[count] >> W[count];
		if (H[count] == 0 && W[count] == 0)
			break;
		count++;
		count1++;
	}
	for (count = 0; count < count1; count++)
	{
		for (int loopH = 0; loopH < H[count] ; loopH++)
		{
			odd++;
			for (int loopW = 0; loopW < W[count] ; loopW++)
			{
				if (odd % 2 == 1)
				{
					cout << "#";
				}
				else
				{
					cout << ".";
				}
				odd++;
			}
			cout<<endl;
		}
		odd = 3;
		cout<<endl;
	}

	return 0;
}

