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