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