#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  while (cin >> h >> w && h || w) {
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) {
        if (i == 0 || i % 2 == 0) {
          if (j == 0 || j % 2 == 0) {
            cout << "#";
          } else {
            cout << ".";
          }
        } else {
          if (j % 2 == 1) {
            cout << ".";
          } else {
            cout << "#";
          }
        }
      }
      cout << endl;
    }
  }
  return 0;
}
