#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int tate, yoko;
  for (int a = 0; a <= 10; a++) {
    cin >> tate >> yoko;
    if (tate == 0 || yoko == 0) break;
    for (int i = 1; i <= tate; i++) {
      for (int j = 1; j <= yoko; j++) {
        if ((i + j) % 2 == 0) {
          cout << "#";
        } else {
          cout << ".";
        }
      }
      cout << endl;
    }
    cout << endl;
  }
}
