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