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