#include <bits/stdc++.h>
std::vector<std::vector<int>> vec;
int x[2];
std::string str = "#.";
int main() {
  do {
    std::cin >> x[0] >> x[1];
    if (x[0] != 0 && x[1] != 0) vec.push_back(std::vector<int>{x[0], x[1]});
  } while (x[0] != 0 && x[1] != 0);
  for (auto v : vec) {
    str = "#.";
    for (int i = 0; i < v[0]; ++i) {
      for (int j = 0; j < v[0] / 2; ++j) {
        std::cout << str;
      }
      if (v[0] % 2 != 0) str[1] == '.' ? std::cout << "#" : std::cout << ".";
      std::cout << std::endl;
      std::reverse(str.begin(), str.end());
    }
    std::cout << std::endl;
  }
  return 0;
}
