#include <bits/stdc++.h>
using namespace std;
int main() {
  char mark[] = "#.";
  int t, H, W;
  do {
    t = 1;
    cin >> H >> W;
    for (int i = 0; i < H; i++) {
      t = i % 2;
      for (int j = 0; j < W; j++) {
        cout << mark[t];
        t = (t + 1) % 2;
      }
      cout << endl;
    }
    cout << endl;
  } while (H != 0 && W != 0);
  cout << endl;
  return 0;
}
