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