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