#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  while (1) {
    cin >> h >> w;
    if (h == 0 && w == 0) break;
    for (int i = 0; i < h / 2; i++) {
      for (int i = 0; i < w / 2; i++) {
        cout << "#.";
      }
      if (w % 2 == 1) {
        cout << "#";
      }
      cout << "\n";
      for (int i = 0; i < w / 2; i++) {
        cout << ".#";
      }
      if (w % 2 == 1) {
        cout << ".";
      }
      cout << "\n";
    }
    if (h % 2 == 1) {
      for (int i = 0; i < w / 2; i++) {
        cout << "#.";
      }
      if (w / 2 == 1) {
        cout << "#";
      }
      cout << "\n";
    }
    cout << "\n";
  }
}
