#include <bits/stdc++.h>
using namespace std;
int main() {
  while (true) {
    int h, w;
    cin >> h >> w;
    if (!h && !w) break;
    bool b1 = true;
    for (int i = 0; i < w; ++i) {
      bool b2 = b1;
      for (int j = 0; j < h; ++j) {
        if (b2)
          cout << "#";
        else
          cout << ".";
        b2 = not b2;
      }
      cout << "\n";
      b1 = not b1;
    }
    cout << "\n";
  }
}
