#include <bits/stdc++.h>
using namespace std;
int main() {
  int W, H;
  bool flag = true;
  while (cin >> H >> W) {
    if (H == 0 && W == 0) {
      break;
    }
    for (int row = 0; row < H; ++row) {
      for (int col = 0; col < W; ++col) {
        cout << (flag ? "#" : ".");
        flag = !flag;
      }
      cout << "\n";
      if (W % 2 == 0) {
        flag = !flag;
      }
    }
    cout << "\n";
  }
}
