#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  while ((H != 0) || (W != 0)) {
    for (int i = 0; i < H * W; i++) {
      if (i + 1 % W == 0) cout << endl;
      if (i % 2 == 0)
        cout << "#";
      else
        cout << ".";
    }
    cout << endl << endl;
    cin >> H >> W;
  }
  return 0;
}
