#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y;
  while (cin >> x >> y) {
    if (x == 0 && y == 0) break;
    for (int l = 1; l <= x; l++) {
      if (l / 2 == 1) {
        for (int k = 1; k <= y / 2; k++) {
          cout << "#";
          cout << ".";
        }
        if (y % 2 == 1)
          cout << "#" << endl;
        else
          cout << endl;
      }
      if (l / 2 == 0) {
        for (int s = 1; s <= y / 2; s++) {
          cout << ".";
          cout << "#";
        }
        if (y % 2 == 1)
          cout << "." << endl;
        else
          cout << endl;
      }
    }
    cout << endl;
  }
}
