#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  while (1) {
    cin >> h >> w;
    if (h == 0 && w == 0) break;
    for (int i = 1; i <= h; h++) {
      if (i % 2 == 0) {
        for (int j = 1; j <= w; j++) {
          if (j % 2 == 0) {
            cout << "#";
          } else {
            cout << ".";
          }
        }
      } else {
        for (int j = 1; j <= w; j++) {
          if (j % 3 == 0) {
            cout << "#";
          } else {
            cout << ".";
          }
        }
      }
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
