#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  while (cin >> a >> b, a) {
    for (int i = 1; i <= a; i++) {
      for (int j = 1; j <= b; j++) {
        if ((i * j) % 2 == 0) {
          cout << '#';
        } else {
          cout << '.';
        }
      }
      cout << endl;
    }
    cout << endl;
  }
}
