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