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