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