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