#include <bits/stdc++.h>
using namespace std;
int main() {
  int h[1000], w[1000];
  int eoi;
  for (int i = 0;; i++) {
    cin >> h[i] >> w[i];
    if (h[i] == 0 && w[i] == 0) {
      eoi = i;
      break;
    }
  }
  for (int i = 0; i < eoi; i++) {
    for (int j = 0; j < h[i] - 1; j++) {
      for (int k = 0; k < w[i] - 1; k++) {
        if (j % 2 == 0 && k % 2 == 0) {
          cout << "#";
        } else if (j % 2 == 0 && k % 2 == 1) {
          cout << ".";
        } else if (j % 2 == 1 && k % 2 == 0) {
          cout << ".";
        } else if (j % 2 == 1 & k % 2 == 1) {
          cout << "#";
        }
      }
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
