#include <bits/stdc++.h>
using namespace std;
int main() {
  int a = 1, b = 1, i = 1;
  while ((a != 0) || (b != 0)) {
    if (i != 1) cout << endl;
    i++;
    cin >> a >> b;
    if ((a != 0) || (b != 0))
      for (int i = 1; i <= a; i++) {
        for (int j = 1; j <= b; j++) {
          if ((i % 2 == 0) && (j % 2 == 1))
            cout << '#';
          else if ((i % 2 == 1) && (j % 2 == 0))
            cout << '#';
          else
            cout << '.';
        }
        cout << endl;
      }
  }
}
