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