#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; i++) {
      for (int j = 0; j < w; j++) {
        if ((i + j) % 2 == 0) {
          cout << "#";
        } else {
          cout << ".";
        }
      }
      cout << endl;
    }
    cout << endl;
  }
}
