#include<iostream>
using namespace std;
int main()
{
	int i,j,H,W;
	char inic,midc;
	while(1)
	{
		inic = "o";
		midc = "o";
		cin >> H >>W;
		if ((H==0) && (W==0)) break;
		for (i=0;i<H;i++)
		{
			switch(inic){
			  case "o":
				inic = "#";
				break;
			  case "#":
				inic = ".";
				break;
			  case ".":
				inic = "#";
				break;
			}
			cout << inic;
			midc = inic;
			for (j=0; j<W; j++)
			{
				switch(midc){
				  case "#":
					midc = ".";
					break;
				  case ".":
					midc = "#";
					break;
				}
				cout << midc;
			}
			cout << endl;
		}
		cout << endl;
	}
	return 0;
}