#include <bits/stdc++.h>
using namespace std;
int main() {
  string line1, line2;
  int h, w;
  cin >> h >> w;
  while (h != 0 || w != 0) {
    for (int i = 0; i < w; i++) {
      if (i % 2 == 0) {
        line1 += "#";
        line2 += ".";
      } else {
        line1 += ".";
        line2 += "#";
      }
    }
    for (int i = 0; i < w; i++) {
      if (i % 2 == 0) {
        cout << line1 << endl;
      } else {
        cout << line2 << endl;
      }
    }
    cout << endl;
    line1 = line2 = "";
    cin >> h >> w;
  }
  return 0;
}
