#include <bits/stdc++.h>
using namespace std;
int main() {
  int h = 1e9, w = 1e9;
  while (cin >> h >> w && (h && w)) {
    for (int i = 0; i < h; i++) {
      for (int j = 0; j < w; j++) cout << "#."[(i & 1 + j & 1) & 1];
      cout << endl;
    }
  }
}
