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