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