#include <bits/stdc++.h>
using namespace std;
void chess(int a) {
  if (a % 2 == 0)
    cout << ".";
  else
    cout << "#";
}
void chessboard(int a, int b) {
  if (b % 2 == 0) {
    for (int i = 0; i < a; i++) chess(i);
    cout << endl;
  } else {
    for (int i = 1; i <= a; i++) chess(i);
    cout << endl;
  }
}
int main() {
  int a, b;
  while (cin >> a >> b) {
    if (a == 0 && b == 0) break;
    for (int i = 1; i <= a; i++) chessboard(b, a);
    cout << endl;
  }
  return 0;
}
