#include <bits/stdc++.h>
int main() {
  while (1) {
    int H, W;
    std::cin >> H >> W;
    if (H == 0 && W == 0) {
      break;
    } else
      for (int j = 0; j < H;) {
        for (int i = 0; i < W;) {
          std::cout << "#";
          i++;
          std::cout << ".";
          i++;
        }
        std::cout << std::endl;
        j++;
        for (int k = 0; k < W;) {
          std::cout << ".";
          k++;
          std::cout << "#";
          k++;
        }
        std::cout << std::endl;
        j++;
      }
    std::cout << std::endl;
  }
  return 0;
}
