#include <bits/stdc++.h>
using namespace std;
int a = 0, b = 0, c = 0, d = 0;
int main() {
  while (1) {
    cin >> a >> b;
    if (a == 0 && b == 0) {
      break;
    }
    for (int i = 0; i < a; i++) {
      for (int y = 0; y < b; y++) {
        if (d > 1) {
          d = 0;
        }
        if (c == 0) {
          cout << "#";
          c++;
          d++;
          if (y == b - 1 && b > 3) {
            c = 0;
          }
        } else if (c == 1) {
          cout << ".";
          c = 0;
          d++;
          if (y == b - 1) {
            c = 1;
          }
          if (y == b - 1 && y == 3) {
          }
        }
      }
      cout << endl;
    }
    cout << endl;
    c = 0;
  }
}
