#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, H, W;
  int x = (i + j) / 2;
  while (true) {
    cin >> H >> W;
    if (H == 0 && W == 0) break;
    for (i = 1; i <= H; i++) {
      for (j = 1; j <= W; j++) {
        if (i + j == 2 * x) {
          cout << "#";
        } else {
          cout << ".";
        }
      }
      cout << endl;
    }
    cout << endl;
  }
}
