#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, ch = 1;
  while (1) {
    cin >> h >> w;
    if (h == 0) break;
    for (int i = 1; i <= h; i++) {
      for (int j = 1; j <= w; j++) {
        if (ch == 1) {
          cout << '#';
          ch = 0;
        } else {
          cout << '.';
          ch = 1;
        }
      }
      cout << '\n';
    }
    cout << '\n';
  }
  return 0;
}
