#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, w;
  for (a = 0;; a++) {
    cin >> H >> W;
    if (H == 0 && W == 0) break;
    h = H / 2;
    w = W / 2;
    if (H % 2 == 0 && W % 2 == 0) {
      for (b = 0; b < h; b++) {
        for (c = 0; c < w; c++) {
          cout << "#"
               << ".";
        }
        cout << endl;
        for (d = 0; d < w; d++) {
          cout << "."
               << "#";
        }
        cout << endl;
      }
    }
    if (H % 2 == 1 && W % 2 == 0) {
      for (e = 0; e < h; e++) {
        for (f = 0; f < w; f++) {
          cout << "#"
               << ".";
        }
        cout << endl;
        for (g = 0; g < w; g++) {
          cout << "."
               << "#";
        }
        cout << endl;
      }
      for (i = 0; i > w; i++) {
        cout << "#"
             << ".";
      }
    }
    if (H % 2 == 0 && W % 2 == 1) {
      for (j = 0; j < h; j++) {
        for (k = 0; k < w; k++) {
          cout << "#"
               << ".";
        }
        cout << "#" << endl;
        for (l = 0; l < w; l++) {
          cout << "."
               << "#";
        }
        cout << "." << endl;
      }
    }
    if (H % 2 == 1 && W % 2 == 1) {
      for (m = 0; m < h; m++) {
        for (n = 0; n < w; n++) {
          cout << "#"
               << ".";
        }
        cout << "#" << endl;
        for (o = 0; o < o; l++) {
          cout << "."
               << "#";
        }
        cout << "." << endl;
      }
      for (p = 0; p < w; p++) {
        cout << "#"
             << ".";
      }
      cout << "#" << endl;
    }
    cout << endl;
  }
  return 0;
}
