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