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